[{"type":"journal_article","author":[{"full_name":"Wurtz, Jonathan","last_name":"Wurtz","first_name":"Jonathan"},{"full_name":"Sack, Stefan","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","last_name":"Sack","orcid":"0000-0001-5400-8508","first_name":"Stefan"},{"full_name":"Wang, Sheng-Tao","last_name":"Wang","first_name":"Sheng-Tao"}],"acknowledgement":"The authors would like to thank Alexander Keesling, Maddie Cain, Nate Gemelke, and Phillip Weinberg for helpful discussions and Danylo Lykov who had early contributions to this work.\r\n10.13039/100000185-Defense Advanced Research Projects Agency Noisy Intermediate-Scale Quantum Devices (Grant Number: W911NF2010021), DARPA Small Business Technology Transfer program (Grant Number: 140D0422C0035).","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","file_date_updated":"2025-01-27T15:03:09Z","OA_place":"publisher","_id":"18923","oa":1,"page":"1-14","intvolume":"         5","ddc":["530"],"file":[{"checksum":"19b84e35cba05bde72bfe7e0b54c3e6c","date_created":"2025-01-27T15:03:09Z","file_size":1753095,"relation":"main_file","access_level":"open_access","success":1,"content_type":"application/pdf","date_updated":"2025-01-27T15:03:09Z","file_name":"2024_IEEEQuantumComputing_Wurtz.pdf","creator":"dernst","file_id":"18924"}],"language":[{"iso":"eng"}],"publication":"IEEE Transactions on Quantum Engineering","has_accepted_license":"1","status":"public","scopus_import":"1","date_created":"2025-01-27T15:00:44Z","title":"Solving nonnative combinatorial optimization problems using hybrid quantum–classical algorithms","department":[{"_id":"MaSe"}],"month":"08","date_updated":"2025-01-27T15:06:15Z","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"doi":"10.1109/tqe.2024.3443660","publication_identifier":{"issn":["2689-1808"]},"publisher":"Institute of Electrical and Electronics Engineers ","article_processing_charge":"Yes (in subscription journal)","publication_status":"published","citation":{"ieee":"J. Wurtz, S. Sack, and S.-T. Wang, “Solving nonnative combinatorial optimization problems using hybrid quantum–classical algorithms,” <i>IEEE Transactions on Quantum Engineering</i>, vol. 5. Institute of Electrical and Electronics Engineers , pp. 1–14, 2024.","mla":"Wurtz, Jonathan, et al. “Solving Nonnative Combinatorial Optimization Problems Using Hybrid Quantum–Classical Algorithms.” <i>IEEE Transactions on Quantum Engineering</i>, vol. 5, Institute of Electrical and Electronics Engineers , 2024, pp. 1–14, doi:<a href=\"https://doi.org/10.1109/tqe.2024.3443660\">10.1109/tqe.2024.3443660</a>.","ista":"Wurtz J, Sack S, Wang S-T. 2024. Solving nonnative combinatorial optimization problems using hybrid quantum–classical algorithms. IEEE Transactions on Quantum Engineering. 5, 1–14.","ama":"Wurtz J, Sack S, Wang S-T. Solving nonnative combinatorial optimization problems using hybrid quantum–classical algorithms. <i>IEEE Transactions on Quantum Engineering</i>. 2024;5:1-14. doi:<a href=\"https://doi.org/10.1109/tqe.2024.3443660\">10.1109/tqe.2024.3443660</a>","chicago":"Wurtz, Jonathan, Stefan Sack, and Sheng-Tao Wang. “Solving Nonnative Combinatorial Optimization Problems Using Hybrid Quantum–Classical Algorithms.” <i>IEEE Transactions on Quantum Engineering</i>. Institute of Electrical and Electronics Engineers , 2024. <a href=\"https://doi.org/10.1109/tqe.2024.3443660\">https://doi.org/10.1109/tqe.2024.3443660</a>.","short":"J. Wurtz, S. Sack, S.-T. Wang, IEEE Transactions on Quantum Engineering 5 (2024) 1–14.","apa":"Wurtz, J., Sack, S., &#38; Wang, S.-T. (2024). Solving nonnative combinatorial optimization problems using hybrid quantum–classical algorithms. <i>IEEE Transactions on Quantum Engineering</i>. Institute of Electrical and Electronics Engineers . <a href=\"https://doi.org/10.1109/tqe.2024.3443660\">https://doi.org/10.1109/tqe.2024.3443660</a>"},"date_published":"2024-08-14T00:00:00Z","year":"2024","OA_type":"hybrid","article_type":"original","abstract":[{"text":"Combinatorial optimization is a challenging problem applicable in a wide range of fields from logistics to finance. Recently, quantum computing has been used to attempt to solve these problems using a range of algorithms, including parameterized quantum circuits, adiabatic protocols, and quantum annealing. These solutions typically have several challenges: 1) there is little to no performance gain over classical methods; 2) not all constraints and objectives may be efficiently encoded in the quantum ansatz; and 3) the solution domain of the objective function may not be the same as the bit strings of measurement outcomes. This work presents “nonnative hybrid algorithms”: a framework to overcome these challenges by integrating quantum and classical resources with a hybrid approach. By designing nonnative quantum variational anosatzes that inherit some but not all problem structure, measurement outcomes from the quantum computer can act as a resource to be used by classical routines to indirectly compute optimal solutions, partially overcoming the challenges of contemporary quantum optimization approaches. These methods are demonstrated using a publicly available neutral-atom quantum computer on two simple problems of Max k-Cut and maximum independent set. We find improvements in solution quality when comparing the hybrid algorithm to its “no quantum” version, a demonstration of a “comparative advantage.”","lang":"eng"}],"quality_controlled":"1","day":"14","volume":5,"oa_version":"Published Version"},{"oa_version":"Preprint","volume":132,"day":"30","external_id":{"arxiv":["2201.10220"],"isi":["001179276700003"],"pmid":["38364163"]},"quality_controlled":"1","article_type":"original","abstract":[{"text":"The lattice Schwinger model, the discrete version of QED in \r\n1\r\n+\r\n1\r\n dimensions, is a well-studied test bench for lattice gauge theories. Here, we study the fractal properties of this model. We reveal the self-similarity of the ground state, which allows us to develop a recurrent procedure for finding the ground-state wave functions and predicting ground-state energies. We present the results of recurrently calculating ground-state wave functions using the fractal Ansatz and automized software package for fractal image processing. In certain parameter regimes, just a few terms are enough for our recurrent procedure to predict ground-state energies close to the exact ones for several hundreds of sites. Our findings pave the way to understanding the complexity of calculating many-body wave functions in terms of their fractal properties as well as finding new links between condensed matter and high-energy lattice models.","lang":"eng"}],"main_file_link":[{"url":"https://doi.org/10.48550/arXiv.2201.10220","open_access":"1"}],"citation":{"ista":"Petrova E, Tiunov ES, Bañuls MC, Fedorov AK. 2024. Fractal states of the Schwinger model. Physical Review Letters. 132(5), 050401.","ieee":"E. Petrova, E. S. Tiunov, M. C. Bañuls, and A. K. Fedorov, “Fractal states of the Schwinger model,” <i>Physical Review Letters</i>, vol. 132, no. 5. American Physical Society, 2024.","mla":"Petrova, Elena, et al. “Fractal States of the Schwinger Model.” <i>Physical Review Letters</i>, vol. 132, no. 5, 050401, American Physical Society, 2024, doi:<a href=\"https://doi.org/10.1103/PhysRevLett.132.050401\">10.1103/PhysRevLett.132.050401</a>.","short":"E. Petrova, E.S. Tiunov, M.C. Bañuls, A.K. Fedorov, Physical Review Letters 132 (2024).","apa":"Petrova, E., Tiunov, E. S., Bañuls, M. C., &#38; Fedorov, A. K. (2024). Fractal states of the Schwinger model. <i>Physical Review Letters</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevLett.132.050401\">https://doi.org/10.1103/PhysRevLett.132.050401</a>","ama":"Petrova E, Tiunov ES, Bañuls MC, Fedorov AK. Fractal states of the Schwinger model. <i>Physical Review Letters</i>. 2024;132(5). doi:<a href=\"https://doi.org/10.1103/PhysRevLett.132.050401\">10.1103/PhysRevLett.132.050401</a>","chicago":"Petrova, Elena, Egor S. Tiunov, Mari Carmen Bañuls, and Aleksey K. Fedorov. “Fractal States of the Schwinger Model.” <i>Physical Review Letters</i>. American Physical Society, 2024. <a href=\"https://doi.org/10.1103/PhysRevLett.132.050401\">https://doi.org/10.1103/PhysRevLett.132.050401</a>."},"year":"2024","date_published":"2024-01-30T00:00:00Z","doi":"10.1103/PhysRevLett.132.050401","publication_identifier":{"eissn":["1079-7114"],"issn":["0031-9007"]},"publisher":"American Physical Society","article_processing_charge":"No","publication_status":"published","department":[{"_id":"MaSe"}],"month":"01","date_updated":"2025-09-04T12:02:33Z","isi":1,"article_number":"050401","title":"Fractal states of the Schwinger model","scopus_import":"1","date_created":"2024-02-18T23:01:00Z","status":"public","language":[{"iso":"eng"}],"publication":"Physical Review Letters","pmid":1,"intvolume":"       132","oa":1,"arxiv":1,"_id":"15002","issue":"5","type":"journal_article","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","acknowledgement":"We thank A. Bargov, I. Khaymovich, and V. Tiunova for fruitful discussions and for useful comments. M. C. B. thanks S. Kühn for discussions about the phase structure of the model. A. K. F. thanks V. Gritsev and A. Garkun for insightful comments. E. V. P., E. S. T., and A. K. F. are\r\nsupported by the RSF Grant No. 20-42-05002 (studying the fractal Ansatz) and the Roadmap on Quantum Computing (Contract No. 868-1.3-15/15-2021, October 5, 2021; calculating on GS energies). A. K. F. thanks the Priority 2030 program at the NIST “MISIS” under the project No. K1-2022-027. M. C. B. was partly funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) under Germany’s Excellence Strategy—EXC-2111–390814868.","author":[{"last_name":"Petrova","full_name":"Petrova, Elena","id":"0ac84990-897b-11ed-a09c-f5abb56a4ede","first_name":"Elena"},{"first_name":"Egor S.","full_name":"Tiunov, Egor S.","last_name":"Tiunov"},{"full_name":"Bañuls, Mari Carmen","last_name":"Bañuls","first_name":"Mari Carmen"},{"first_name":"Aleksey K.","last_name":"Fedorov","full_name":"Fedorov, Aleksey K."}]},{"date_created":"2024-03-17T23:00:59Z","status":"public","scopus_import":"1","language":[{"iso":"eng"}],"publication":"Physical Review Research","has_accepted_license":"1","ddc":["530"],"file":[{"file_size":2777593,"relation":"main_file","access_level":"open_access","success":1,"checksum":"274c9f1b15b3547a10a03f39e4ccc582","date_created":"2024-03-19T07:16:38Z","file_id":"15123","creator":"dernst","content_type":"application/pdf","file_name":"2024_PhysicalReviewResearch_Sack.pdf","date_updated":"2024-03-19T07:16:38Z"}],"intvolume":"         6","oa":1,"arxiv":1,"DOAJ_listed":"1","_id":"15122","issue":"1","corr_author":"1","file_date_updated":"2024-03-19T07:16:38Z","type":"journal_article","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"orcid":"0000-0001-5400-8508","first_name":"Stefan","last_name":"Sack","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","full_name":"Sack, Stefan"},{"first_name":"Daniel J.","last_name":"Egger","full_name":"Egger, Daniel J."}],"acknowledgement":"S.H.S. acknowledges support from the IBM Ph.D. fellowship 2022 in quantum computing. The authors also thank M. Serbyn, R. Kueng, R. A. Medina, and S. Woerner for fruitful discussions.","volume":6,"day":"01","oa_version":"Published Version","project":[{"name":"IMB PhD Nomination Fellowship - Stefan Sack","_id":"bd660c93-d553-11ed-ba76-fb0fb6f49c0d"}],"quality_controlled":"1","external_id":{"arxiv":["2307.14427"]},"article_type":"original","abstract":[{"lang":"eng","text":"Quantum computers are increasing in size and quality but are still very noisy. Error mitigation extends the size of the quantum circuits that noisy devices can meaningfully execute. However, state-of-the-art error mitigation methods are hard to implement and the limited qubit connectivity in superconducting qubit devices restricts most applications to the hardware's native topology. Here we show a quantum approximate optimization algorithm (QAOA) on nonplanar random regular graphs with up to 40 nodes enabled by a machine learning-based error mitigation. We use a swap network with careful decision-variable-to-qubit mapping and a feed-forward neural network to optimize a depth-two QAOA on up to 40 qubits. We observe a meaningful parameter optimization for the largest graph which requires running quantum circuits with 958 two-qubit gates. Our paper emphasizes the need to mitigate samples, and not only expectation values, in quantum approximate optimization. These results are a step towards executing quantum approximate optimization at a scale that is not classically simulable. Reaching such system sizes is key to properly understanding the true potential of heuristic algorithms like QAOA."}],"citation":{"chicago":"Sack, Stefan, and Daniel J. Egger. “Large-Scale Quantum Approximate Optimization on Nonplanar Graphs with Machine Learning Noise Mitigation.” <i>Physical Review Research</i>. American Physical Society, 2024. <a href=\"https://doi.org/10.1103/PhysRevResearch.6.013223\">https://doi.org/10.1103/PhysRevResearch.6.013223</a>.","ama":"Sack S, Egger DJ. Large-scale quantum approximate optimization on nonplanar graphs with machine learning noise mitigation. <i>Physical Review Research</i>. 2024;6(1). doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.6.013223\">10.1103/PhysRevResearch.6.013223</a>","apa":"Sack, S., &#38; Egger, D. J. (2024). Large-scale quantum approximate optimization on nonplanar graphs with machine learning noise mitigation. <i>Physical Review Research</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevResearch.6.013223\">https://doi.org/10.1103/PhysRevResearch.6.013223</a>","short":"S. Sack, D.J. Egger, Physical Review Research 6 (2024).","mla":"Sack, Stefan, and Daniel J. Egger. “Large-Scale Quantum Approximate Optimization on Nonplanar Graphs with Machine Learning Noise Mitigation.” <i>Physical Review Research</i>, vol. 6, no. 1, 013223, American Physical Society, 2024, doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.6.013223\">10.1103/PhysRevResearch.6.013223</a>.","ieee":"S. Sack and D. J. Egger, “Large-scale quantum approximate optimization on nonplanar graphs with machine learning noise mitigation,” <i>Physical Review Research</i>, vol. 6, no. 1. American Physical Society, 2024.","ista":"Sack S, Egger DJ. 2024. Large-scale quantum approximate optimization on nonplanar graphs with machine learning noise mitigation. Physical Review Research. 6(1), 013223."},"date_published":"2024-03-01T00:00:00Z","year":"2024","doi":"10.1103/PhysRevResearch.6.013223","article_processing_charge":"Yes","publisher":"American Physical Society","publication_identifier":{"eissn":["2643-1564"]},"publication_status":"published","department":[{"_id":"MaSe"}],"month":"03","date_updated":"2025-05-14T09:32:15Z","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"article_number":"013223","title":"Large-scale quantum approximate optimization on nonplanar graphs with machine learning noise mitigation"},{"scopus_import":"1","status":"public","date_created":"2024-05-06T09:02:18Z","publication":"SciPost Physics","language":[{"iso":"eng"}],"has_accepted_license":"1","ddc":["530"],"file":[{"access_level":"open_access","success":1,"relation":"main_file","file_size":2733685,"date_created":"2024-05-07T12:58:47Z","checksum":"f999204856417dcf5a736ac8df432b96","file_id":"15369","creator":"dernst","file_name":"2024_SciPostPhys_Babkin.pdf","date_updated":"2024-05-07T12:58:47Z","content_type":"application/pdf"}],"intvolume":"        16","oa":1,"arxiv":1,"_id":"15367","corr_author":"1","issue":"5","file_date_updated":"2024-05-07T12:58:47Z","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","author":[{"full_name":"Babkin, Serafim","id":"41e64307-6672-11ee-b9ad-cc7a0075a479","last_name":"Babkin","orcid":"0009-0003-7382-8036","first_name":"Serafim"},{"orcid":"0000-0003-2607-2363","first_name":"Andrew P","last_name":"Higginbotham","full_name":"Higginbotham, Andrew P","id":"4AD6785A-F248-11E8-B48F-1D18A9856A87"},{"id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn","first_name":"Maksym","orcid":"0000-0002-2399-5827"}],"acknowledgement":"We acknowledge useful discussions with M. Geier, A. Levchenko, B. Ramshaw, T. Scaffidi, and\r\nJ. Shabani. This research was funded by the Austrian Science Fund (FWF) F 86.\r\nFor the purpose of open access, authors have applied a CC BY public copyright licence to any\r\nAuthor Accepted Manuscript version arising from this submission. MS acknowledges hospitality of KITP supported in part by the National Science Foundation under Grants No. NSF\r\nPHY-1748958 and PHY-2309135. APH acknowledges the support of the NOMIS foundation.","type":"journal_article","day":"01","volume":16,"oa_version":"Published Version","quality_controlled":"1","external_id":{"isi":["001215855200002"],"arxiv":["2311.09347"]},"project":[{"name":"Protected states of quantum matter","_id":"eb9b30ac-77a9-11ec-83b8-871f581d53d2"},{"name":"Center for Correlated Quantum Materials and Solid State Quantum Systems:  Probing topology in circuits and quantum materials","_id":"34a7f947-11ca-11ed-8bc3-c5dc2bbaae25","grant_number":"F8609"}],"article_type":"original","abstract":[{"lang":"eng","text":"Two-dimensional semiconductor-superconductor heterostructures form the foundation of numerous nanoscale physical systems. However, measuring the properties of such heterostructures, and characterizing the semiconductor in-situ is challenging. A recent experimental study by [Phys. Rev. Lett. 128, 107701 (2022)] was able to probe the semiconductor within the heterostructure using microwave measurements of the superfluid density. This work revealed a rapid depletion of superfluid density in semiconductor, caused by the in-plane magnetic field which in presence of spin-orbit coupling creates so-called Bogoliubov Fermi surfaces. The experimental work used a simplified theoretical model that neglected the presence of non-magnetic disorder in the semiconductor, hence describing the data only qualitatively. Motivated by experiments, we introduce a theoretical model describing a disordered semiconductor with strong spin-orbit coupling that is proximitized by a superconductor. Our model provides specific predictions for the density of states and superfluid density. Presence of disorder leads to the emergence of a gapless superconducting phase, that may be viewed as a manifestation of Bogoliubov Fermi surface. When applied to real experimental data, our model showcases excellent quantitative agreement, enabling the extraction of material parameters such as mean free path and mobility, and estimating g-tensor after taking into account the orbital contribution of magnetic field. Our model can be used to probe in-situ parameters of other superconductor-semiconductor heterostructures and can be further extended to give access to transport properties."}],"year":"2024","date_published":"2024-05-01T00:00:00Z","citation":{"ieee":"S. Babkin, A. P. Higginbotham, and M. Serbyn, “Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor in magnetic field,” <i>SciPost Physics</i>, vol. 16, no. 5. SciPost Foundation, 2024.","mla":"Babkin, Serafim, et al. “Proximity-Induced Gapless Superconductivity in Two-Dimensional Rashba Semiconductor in Magnetic Field.” <i>SciPost Physics</i>, vol. 16, no. 5, 115, SciPost Foundation, 2024, doi:<a href=\"https://doi.org/10.21468/scipostphys.16.5.115\">10.21468/scipostphys.16.5.115</a>.","ista":"Babkin S, Higginbotham AP, Serbyn M. 2024. Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor in magnetic field. SciPost Physics. 16(5), 115.","ama":"Babkin S, Higginbotham AP, Serbyn M. Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor in magnetic field. <i>SciPost Physics</i>. 2024;16(5). doi:<a href=\"https://doi.org/10.21468/scipostphys.16.5.115\">10.21468/scipostphys.16.5.115</a>","chicago":"Babkin, Serafim, Andrew P Higginbotham, and Maksym Serbyn. “Proximity-Induced Gapless Superconductivity in Two-Dimensional Rashba Semiconductor in Magnetic Field.” <i>SciPost Physics</i>. SciPost Foundation, 2024. <a href=\"https://doi.org/10.21468/scipostphys.16.5.115\">https://doi.org/10.21468/scipostphys.16.5.115</a>.","short":"S. Babkin, A.P. Higginbotham, M. Serbyn, SciPost Physics 16 (2024).","apa":"Babkin, S., Higginbotham, A. P., &#38; Serbyn, M. (2024). Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor in magnetic field. <i>SciPost Physics</i>. SciPost Foundation. <a href=\"https://doi.org/10.21468/scipostphys.16.5.115\">https://doi.org/10.21468/scipostphys.16.5.115</a>"},"publication_identifier":{"issn":["2542-4653"]},"article_processing_charge":"Yes","publisher":"SciPost Foundation","doi":"10.21468/scipostphys.16.5.115","publication_status":"published","date_updated":"2025-09-04T13:53:20Z","department":[{"_id":"MaSe"},{"_id":"AnHi"}],"month":"05","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"isi":1,"article_number":"115","title":"Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor in magnetic field"},{"project":[{"call_identifier":"H2020","_id":"fc2ed2f7-9c52-11eb-aca3-c01059dda49c","name":"IST-BRIDGE: International postdoctoral program","grant_number":"101034413"}],"has_accepted_license":"1","keyword":["quantum many-body scars","non-equilibrium physics","non-Hermitian physics"],"date_created":"2024-08-30T12:59:43Z","status":"public","ec_funded":1,"day":"30","oa_version":"None","ddc":["530"],"abstract":[{"lang":"eng","text":"Mechanisms for suppressing thermalization in disorder-free many-body systems, such as Hilbert space fragmentation and quantum many-body scars, have recently attracted much interest in foundations of quantum statistical physics and potential quantum information processing applications. However,  their sensitivity to realistic effects such as finite temperature remains largely unexplored. Here, we have utilized IBM's Kolkata quantum processor to demonstrate an unexpected robustness of quantum many-body scars at finite temperatures when the system is prepared in a thermal Gibbs ensemble. We identify such robustness in the PXP model, which describes quantum many-body scars in experimental systems of Rydberg atom arrays and ultracold atoms in tilted Bose--Hubbard optical lattices. By contrast, other theoretical models which host exact quantum many-body scars are found to lack such robustness, and their scarring properties quickly decay with temperature. Our study sheds light on the important differences between scarred models in terms of their algebraic structures, which impacts their resilience to finite temperature."}],"file":[{"date_created":"2024-08-30T12:55:37Z","checksum":"2bd49ce5a63f1951c1ed3d89cce4fe27","success":1,"access_level":"open_access","file_size":322400,"relation":"main_file","file_name":"FiguresData.zip","date_updated":"2024-08-30T12:55:37Z","content_type":"application/zip","file_id":"17472","creator":"jdesaule"},{"creator":"jdesaule","file_id":"17473","file_name":"readme.txt","date_updated":"2024-08-30T13:19:57Z","content_type":"text/plain","access_level":"open_access","success":1,"relation":"main_file","file_size":1368,"date_created":"2024-08-30T13:19:57Z","checksum":"c2ba113a241e98c394cc3ca21f3fa126"}],"publisher":"Institute of Science and Technology Austria","article_processing_charge":"No","doi":"10.15479/AT:ISTA:17471","_id":"17471","year":"2024","related_material":{"record":[{"relation":"used_in_publication","id":"18627","status":"public"}]},"date_published":"2024-08-30T00:00:00Z","oa":1,"citation":{"apa":"Desaules, J.-Y. M. (2024). Data for “Enhanced many-body quantum scars from the non-Hermitian Fock skin effect.” Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT:ISTA:17471\">https://doi.org/10.15479/AT:ISTA:17471</a>","short":"J.-Y.M. Desaules, (2024).","chicago":"Desaules, Jean-Yves Marc. “Data for ‘Enhanced Many-Body Quantum Scars from the Non-Hermitian Fock Skin Effect.’” Institute of Science and Technology Austria, 2024. <a href=\"https://doi.org/10.15479/AT:ISTA:17471\">https://doi.org/10.15479/AT:ISTA:17471</a>.","ama":"Desaules J-YM. Data for “Enhanced many-body quantum scars from the non-Hermitian Fock skin effect.” 2024. doi:<a href=\"https://doi.org/10.15479/AT:ISTA:17471\">10.15479/AT:ISTA:17471</a>","ista":"Desaules J-YM. 2024. Data for ‘Enhanced many-body quantum scars from the non-Hermitian Fock skin effect’, Institute of Science and Technology Austria, <a href=\"https://doi.org/10.15479/AT:ISTA:17471\">10.15479/AT:ISTA:17471</a>.","mla":"Desaules, Jean-Yves Marc. <i>Data for “Enhanced Many-Body Quantum Scars from the Non-Hermitian Fock Skin Effect.”</i> Institute of Science and Technology Austria, 2024, doi:<a href=\"https://doi.org/10.15479/AT:ISTA:17471\">10.15479/AT:ISTA:17471</a>.","ieee":"J.-Y. M. Desaules, “Data for ‘Enhanced many-body quantum scars from the non-Hermitian Fock skin effect.’” Institute of Science and Technology Austria, 2024."},"user_id":"68b8ca59-c5b3-11ee-8790-cd641c68093d","author":[{"orcid":"0000-0002-3749-6375","first_name":"Jean-Yves Marc","full_name":"Desaules, Jean-Yves Marc","id":"6c292945-a610-11ed-9eec-c3be1ad62a80","last_name":"Desaules"}],"type":"research_data","title":"Data for \"Enhanced many-body quantum scars from the non-Hermitian Fock skin effect\"","date_updated":"2025-09-08T14:54:55Z","contributor":[{"contributor_type":"researcher","first_name":"Ruizhe","last_name":"Shen"},{"last_name":"Qin","contributor_type":"researcher","first_name":"Fang"},{"id":"6c292945-a610-11ed-9eec-c3be1ad62a80","last_name":"Desaules","first_name":"Jean-Yves Marc","orcid":"0000-0002-3749-6375","contributor_type":"researcher"},{"contributor_type":"researcher","first_name":"Zlatko","last_name":"Papić"},{"first_name":"Ching Hua","contributor_type":"researcher","last_name":"Lee"}],"department":[{"_id":"MaSe"}],"month":"08","tmp":{"image":"/images/cc_by_nc.png","legal_code_url":"https://creativecommons.org/licenses/by-nc/4.0/legalcode","name":"Creative Commons Attribution-NonCommercial 4.0 International (CC BY-NC 4.0)","short":"CC BY-NC (4.0)"},"file_date_updated":"2024-08-30T13:19:57Z"},{"tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"date_updated":"2025-09-08T09:04:14Z","month":"08","department":[{"_id":"MaSe"}],"title":"Many-body entropies and entanglement from polynomially many local measurements","article_number":"031035","isi":1,"date_published":"2024-08-26T00:00:00Z","year":"2024","citation":{"chicago":"Vermersch, Benoît, Marko Ljubotina, J. Ignacio Cirac, Peter Zoller, Maksym Serbyn, and Lorenzo Piroli. “Many-Body Entropies and Entanglement from Polynomially Many Local Measurements.” <i>Physical Review X</i>. American Physical Society, 2024. <a href=\"https://doi.org/10.1103/physrevx.14.031035\">https://doi.org/10.1103/physrevx.14.031035</a>.","ama":"Vermersch B, Ljubotina M, Cirac JI, Zoller P, Serbyn M, Piroli L. Many-body entropies and entanglement from polynomially many local measurements. <i>Physical Review X</i>. 2024;14(3). doi:<a href=\"https://doi.org/10.1103/physrevx.14.031035\">10.1103/physrevx.14.031035</a>","apa":"Vermersch, B., Ljubotina, M., Cirac, J. I., Zoller, P., Serbyn, M., &#38; Piroli, L. (2024). Many-body entropies and entanglement from polynomially many local measurements. <i>Physical Review X</i>. American Physical Society. <a href=\"https://doi.org/10.1103/physrevx.14.031035\">https://doi.org/10.1103/physrevx.14.031035</a>","short":"B. Vermersch, M. Ljubotina, J.I. Cirac, P. Zoller, M. Serbyn, L. Piroli, Physical Review X 14 (2024).","mla":"Vermersch, Benoît, et al. “Many-Body Entropies and Entanglement from Polynomially Many Local Measurements.” <i>Physical Review X</i>, vol. 14, no. 3, 031035, American Physical Society, 2024, doi:<a href=\"https://doi.org/10.1103/physrevx.14.031035\">10.1103/physrevx.14.031035</a>.","ieee":"B. Vermersch, M. Ljubotina, J. I. Cirac, P. Zoller, M. Serbyn, and L. Piroli, “Many-body entropies and entanglement from polynomially many local measurements,” <i>Physical Review X</i>, vol. 14, no. 3. American Physical Society, 2024.","ista":"Vermersch B, Ljubotina M, Cirac JI, Zoller P, Serbyn M, Piroli L. 2024. Many-body entropies and entanglement from polynomially many local measurements. Physical Review X. 14(3), 031035."},"publication_status":"published","publisher":"American Physical Society","article_processing_charge":"Yes","publication_identifier":{"issn":["2160-3308"]},"doi":"10.1103/physrevx.14.031035","abstract":[{"text":"Estimating global properties of many-body quantum systems such as entropy or bipartite entanglement is a notoriously difficult task, typically requiring a number of measurements or classical postprocessing resources growing exponentially in the system size. In this work, we address the problem of estimating global entropies and mixed-state entanglement via partial-transposed (PT) moments and show that efficient estimation strategies exist under the assumption that all the spatial correlation lengths are finite. Focusing on one-dimensional systems, we identify a set of approximate factorization conditions (AFCs) on the system density matrix, which allow us to reconstruct entropies and PT moments from information on local subsystems. This identification yields a simple and efficient strategy for entropy and entanglement estimation. Our method could be implemented in different ways, depending on how information on local subsystems is extracted. Focusing on randomized measurements providing a practical and common measurement scheme, we prove that our protocol requires only polynomially many measurements and postprocessing operations, assuming that the state to be measured satisfies the AFCs. We prove that the AFCs hold for finite-depth quantum-circuit states and translation-invariant matrix-product density operators and provide numerical evidence that they are satisfied in more general, physically interesting cases, including thermal states of local Hamiltonians. We argue that our method could be practically useful to detect bipartite mixed-state entanglement for large numbers of qubits available in today’s quantum platforms.","lang":"eng"}],"article_type":"original","OA_type":"gold","volume":14,"oa_version":"Published Version","day":"26","ec_funded":1,"quality_controlled":"1","external_id":{"arxiv":["2311.08108"],"isi":["001299667100002"]},"project":[{"grant_number":"850899","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020"}],"file_date_updated":"2024-09-05T09:39:00Z","issue":"3","acknowledgement":"B. V. acknowledges funding from the Austrian Science Foundation (Grant No. FWF, P 32597 N), from the French National Research Agency via the JCJC project QRand (Grant No. ANR-20-CE47-0005), and via the research programs Plan France 2030 EPIQ (Grant No. ANR-22-PETQ-0007), QUBITAF (Grant No. ANR-22-PETQ-0004), and HQI (Grant No. ANR-22-PNCQ-0002). M. L. and M. S. acknowledge support by the European Research Council under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 850899). M. S. acknowledges the hospitality of KITP supported in part by the National Science Foundation under Grants No. NSF PHY-1748958 and No. NSF PHY-2309135. J. I. C. is supported by the Hightech Agenda Bayern Plus through the Munich Quantum Valley and the German Federal Ministry of Education and Research through EQUAHUMO (Grant No. 13N16066). P. Z. acknowledges funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 101113690 (PASQuanS2.1).","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","author":[{"first_name":"Benoît","full_name":"Vermersch, Benoît","last_name":"Vermersch"},{"last_name":"Ljubotina","id":"F75EE9BE-5C90-11EA-905D-16643DDC885E","full_name":"Ljubotina, Marko","orcid":"0000-0003-0038-7068","first_name":"Marko"},{"full_name":"Cirac, J. Ignacio","last_name":"Cirac","first_name":"J. Ignacio"},{"first_name":"Peter","last_name":"Zoller","full_name":"Zoller, Peter"},{"id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn","orcid":"0000-0002-2399-5827","first_name":"Maksym"},{"first_name":"Lorenzo","last_name":"Piroli","full_name":"Piroli, Lorenzo"}],"type":"journal_article","oa":1,"_id":"17493","OA_place":"publisher","arxiv":1,"DOAJ_listed":"1","file":[{"date_created":"2024-09-05T09:39:00Z","checksum":"1b114acc89025120727200681e4e9074","success":1,"access_level":"open_access","file_size":1408836,"relation":"main_file","date_updated":"2024-09-05T09:39:00Z","file_name":"2024_PhysRevX_Vermersch.pdf","content_type":"application/pdf","file_id":"17532","creator":"cchlebak"}],"ddc":["530"],"intvolume":"        14","scopus_import":"1","date_created":"2024-09-04T18:57:11Z","status":"public","APC_amount":"4863,6 EUR","has_accepted_license":"1","publication":"Physical Review X","language":[{"iso":"eng"}]},{"page":"133","file":[{"date_updated":"2024-07-10T11:34:09Z","file_name":"Raimel_Thesis-Final.zip","content_type":"application/zip","file_id":"17212","creator":"rmedinar","date_created":"2024-07-09T09:21:44Z","checksum":"6f45273d04f4418bc2adc018baed0525","access_level":"closed","relation":"source_file","file_size":"14218691"},{"date_created":"2024-07-17T09:23:24Z","checksum":"6724a95bec772dbabc0111b9f08a805e","access_level":"open_access","success":1,"relation":"main_file","file_size":11253627,"file_name":"Raimel_Thesis-20_pdfa.pdf","date_updated":"2024-07-17T09:23:24Z","content_type":"application/pdf","file_id":"17275","creator":"rmedinar"}],"ddc":["539"],"acknowledged_ssus":[{"_id":"ScienComp"}],"has_accepted_license":"1","language":[{"iso":"eng"}],"supervisor":[{"first_name":"Maksym","orcid":"0000-0002-2399-5827","last_name":"Serbyn","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym"}],"date_created":"2024-07-09T09:14:24Z","keyword":["Quantum computing","Variational Quantum Algorithms","Optimization"],"status":"public","type":"dissertation","author":[{"last_name":"Medina Ramos","full_name":"Medina Ramos, Raimel A","id":"CE680B90-D85A-11E9-B684-C920E6697425","first_name":"Raimel A","orcid":"0000-0002-5383-2869"}],"user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","file_date_updated":"2024-07-17T09:23:24Z","corr_author":"1","OA_place":"publisher","_id":"17208","oa":1,"related_material":{"record":[{"id":"10545","status":"public","relation":"part_of_dissertation"},{"relation":"part_of_dissertation","id":"10067","status":"public"},{"relation":"part_of_dissertation","id":"17222","status":"public"},{"relation":"part_of_dissertation","id":"13125","status":"public"},{"relation":"part_of_dissertation","id":"11471","status":"public"}]},"abstract":[{"lang":"eng","text":"Can current quantum computers provide a speedup over their classical counterparts for some kinds of problems? In this thesis, with a focus on ground state search/preparation, we address some of the challenges that both quantum annealing and variational quantum algorithms suffer from, hindering any possible practical speedup in comparison to the best classical counterparts. \r\n\r\nIn the first part of the thesis, we study the performance of quantum annealing for solving a particular combinatorial optimization problem called 3-XOR satisfability (3-XORSAT). The classical problem is mapped into a ground state search of a 3-local classical Hamiltonian $H_C$. We consider how modifying the initial problem, by adding more interaction terms to the corresponding Hamiltonian, leads to the emergence of a first-order phase transition during the annealing process. This phenomenon causes the total annealing duration, $T$, required to prepare the ground state of $H_C$ with a high probability to increase exponentially with the size of the problem. Our findings indicate that with the growing complexity of problem instances, the likelihood of encountering first-order phase transitions also increases, making quantum annealing an impractical solution for these types of combinatorial optimization problems.\r\n\r\nIn the second part, we focus on the problem of barren plateaus in generic variational quantum algorithms. Barren plateaus correspond to flat regions in the parameter space where the gradient of the cost function is zero in expectation, and with the variance decaying exponentially with the system size, thus obstructing an efficient parameter optimization.  We propose an algorithm to circumvent Barren Plateaus by monitoring the entanglement entropy of k-local reduced density matrices, alongside a method for estimating entanglement entropy via classical shadow tomography. We illustrate the approach with the paradigmatic example of the variational quantum eigensolver, and show that our algorithm effectively avoids barren plateaus in the initialization as well as during the optimization stage. \r\n\r\nLastly, in the last two Chapters of this thesis, we focus on the quantum approximate optimization algorithm (QAOA), originally introduced as an algorithm for solving generic combinatorial optimization problems in near-term quantum devices. Specifically, we focus on how to develop rigorous initialization strategies with guarantee improvement. Our motivation for this study lies in that for random initialization, the optimization typically leads to local minima with poor performance. Our main result corresponds to the analytical construction of index-1 saddle points or transition states, stationary points with a single direction of descent, as a tool for systematically exploring the QAOA optimization landscape. This leads us to propose a novel greedy parameter initialization strategy that guarantees for the energy to decrease with an increasing number of circuit layers. Furthermore, with precise estimates for the negative Hessian eigenvalue and its eigenvector, we establish a lower bound for energy improvement following a QAOA iteration."}],"project":[{"call_identifier":"H2020","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","grant_number":"850899"}],"alternative_title":["ISTA Thesis"],"oa_version":"Published Version","day":"09","ec_funded":1,"title":"Exploring the optimization landscape of variational quantum algorithms","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"department":[{"_id":"GradSch"},{"_id":"MaSe"}],"month":"07","date_updated":"2026-04-07T12:43:22Z","publication_status":"published","degree_awarded":"PhD","doi":"10.15479/at:ista:17208","publisher":"Institute of Science and Technology Austria","article_processing_charge":"No","publication_identifier":{"issn":["2663-337X"]},"citation":{"ieee":"R. A. Medina Ramos, “Exploring the optimization landscape of variational quantum algorithms,” Institute of Science and Technology Austria, 2024.","mla":"Medina Ramos, Raimel A. <i>Exploring the Optimization Landscape of Variational Quantum Algorithms</i>. Institute of Science and Technology Austria, 2024, doi:<a href=\"https://doi.org/10.15479/at:ista:17208\">10.15479/at:ista:17208</a>.","ista":"Medina Ramos RA. 2024. Exploring the optimization landscape of variational quantum algorithms. Institute of Science and Technology Austria.","ama":"Medina Ramos RA. Exploring the optimization landscape of variational quantum algorithms. 2024. doi:<a href=\"https://doi.org/10.15479/at:ista:17208\">10.15479/at:ista:17208</a>","chicago":"Medina Ramos, Raimel A. “Exploring the Optimization Landscape of Variational Quantum Algorithms.” Institute of Science and Technology Austria, 2024. <a href=\"https://doi.org/10.15479/at:ista:17208\">https://doi.org/10.15479/at:ista:17208</a>.","short":"R.A. Medina Ramos, Exploring the Optimization Landscape of Variational Quantum Algorithms, Institute of Science and Technology Austria, 2024.","apa":"Medina Ramos, R. A. (2024). <i>Exploring the optimization landscape of variational quantum algorithms</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:17208\">https://doi.org/10.15479/at:ista:17208</a>"},"date_published":"2024-07-09T00:00:00Z","year":"2024"},{"date_published":"2024-05-16T00:00:00Z","related_material":{"record":[{"relation":"dissertation_contains","id":"17208","status":"public"}]},"year":"2024","oa":1,"citation":{"apa":"Medina Ramos, R. A., &#38; Serbyn, M. (n.d.). A recursive lower bound on the energy improvement of the quantum approximate optimization algorithm. <i>arXiv</i>. <a href=\"https://doi.org/10.48550/arXiv.2405.10125\">https://doi.org/10.48550/arXiv.2405.10125</a>","short":"R.A. Medina Ramos, M. Serbyn, ArXiv (n.d.).","chicago":"Medina Ramos, Raimel A, and Maksym Serbyn. “A Recursive Lower Bound on the Energy Improvement of the Quantum Approximate Optimization Algorithm.” <i>ArXiv</i>, n.d. <a href=\"https://doi.org/10.48550/arXiv.2405.10125\">https://doi.org/10.48550/arXiv.2405.10125</a>.","ama":"Medina Ramos RA, Serbyn M. A recursive lower bound on the energy improvement of the quantum approximate optimization algorithm. <i>arXiv</i>. doi:<a href=\"https://doi.org/10.48550/arXiv.2405.10125\">10.48550/arXiv.2405.10125</a>","ista":"Medina Ramos RA, Serbyn M. A recursive lower bound on the energy improvement of the quantum approximate optimization algorithm. arXiv, 2405.10125.","mla":"Medina Ramos, Raimel A., and Maksym Serbyn. “A Recursive Lower Bound on the Energy Improvement of the Quantum Approximate Optimization Algorithm.” <i>ArXiv</i>, 2405.10125, doi:<a href=\"https://doi.org/10.48550/arXiv.2405.10125\">10.48550/arXiv.2405.10125</a>.","ieee":"R. A. Medina Ramos and M. Serbyn, “A recursive lower bound on the energy improvement of the quantum approximate optimization algorithm,” <i>arXiv</i>. ."},"article_processing_charge":"No","doi":"10.48550/arXiv.2405.10125","arxiv":1,"_id":"17222","OA_place":"repository","publication_status":"draft","date_updated":"2026-04-07T12:43:22Z","corr_author":"1","department":[{"_id":"MaSe"}],"month":"05","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"first_name":"Raimel A","orcid":"0000-0002-5383-2869","full_name":"Medina Ramos, Raimel A","id":"CE680B90-D85A-11E9-B684-C920E6697425","last_name":"Medina Ramos"},{"first_name":"Maksym","orcid":"0000-0002-2399-5827","last_name":"Serbyn","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym"}],"article_number":"2405.10125","type":"preprint","title":"A recursive lower bound on the energy improvement of the quantum approximate optimization algorithm","status":"public","date_created":"2024-07-10T13:12:09Z","oa_version":"Preprint","day":"16","publication":"arXiv","language":[{"iso":"eng"}],"external_id":{"arxiv":["2405.10125"]},"abstract":[{"text":"The quantum approximate optimization algorithm (QAOA) uses a quantum computer\r\nto implement a variational method with $2p$ layers of alternating unitary\r\noperators, optimized by a classical computer to minimize a cost function. While\r\nrigorous performance guarantees exist for the QAOA at small depths $p$, the\r\nbehavior at large depths remains less clear, though simulations suggest\r\nexponentially fast convergence for certain problems. In this work, we gain\r\ninsights into the deep QAOA using an analytic expansion of the cost function\r\naround transition states. Transition states are constructed in a recursive\r\nmanner: from the local minima of the QAOA with $p$ layers we obtain transition\r\nstates of the QAOA with $p+1$ layers, which are stationary points characterized\r\nby a unique direction of negative curvature. We construct an analytic estimate\r\nof the negative curvature and the corresponding direction in parameter space at\r\neach transition state. The expansion of the QAOA cost function along the\r\nnegative direction to the quartic order gives a lower bound of the QAOA cost\r\nfunction improvement. We provide physical intuition behind the analytic\r\nexpressions for the local curvature and quartic expansion coefficient. Our\r\nnumerical study confirms the accuracy of our approximations and reveals that\r\nthe obtained bound and the true value of the QAOA cost function gain have a\r\ncharacteristic exponential decrease with the number of layers $p$, with the\r\nbound decreasing more rapidly. Our study establishes an analytical method for\r\nrecursively studying the QAOA that is applicable in the regime of high circuit\r\ndepth.","lang":"eng"}],"main_file_link":[{"url":"https://doi.org/10.48550/arXiv.2405.10125","open_access":"1"}]},{"project":[{"call_identifier":"H2020","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","grant_number":"850899"}],"external_id":{"arxiv":["2303.16876"]},"quality_controlled":"1","ec_funded":1,"volume":108,"oa_version":"Published Version","day":"01","article_type":"original","abstract":[{"text":"The many-body localization (MBL) proximity effect is an intriguing phenomenon where a thermal bath localizes due to the interaction with a disordered system. The interplay of thermal and nonergodic behavior in these systems gives rise to a rich phase diagram, whose exploration is an active field of research. In this paper, we study a bosonic Hubbard model featuring two particle species representing the bath and the disordered system. Using state-of-the-art numerical techniques, we investigate the dynamics of the model in different regimes, based on which we obtain a tentative phase diagram as a function of coupling strength and bath size. When the bath is composed of a single particle, we observe clear signatures of a transition from an MBL proximity effect to a delocalized phase. Increasing the bath size, however, its thermalizing effect becomes stronger and eventually the whole system delocalizes in the range of moderate interaction strengths studied. In this regime, we characterize particle transport, revealing diffusive behavior of the originally localized bosons.","lang":"eng"}],"doi":"10.1103/physrevb.108.054201","publisher":"American Physical Society","article_processing_charge":"Yes (in subscription journal)","publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"publication_status":"published","citation":{"mla":"Brighi, Pietro, et al. “Many-Body Localization Proximity Effect in a Two-Species Bosonic Hubbard Model.” <i>Physical Review B</i>, vol. 108, no. 5, 054201, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/physrevb.108.054201\">10.1103/physrevb.108.054201</a>.","ieee":"P. Brighi, M. Ljubotina, D. A. Abanin, and M. Serbyn, “Many-body localization proximity effect in a two-species bosonic Hubbard model,” <i>Physical Review B</i>, vol. 108, no. 5. American Physical Society, 2023.","ista":"Brighi P, Ljubotina M, Abanin DA, Serbyn M. 2023. Many-body localization proximity effect in a two-species bosonic Hubbard model. Physical Review B. 108(5), 054201.","chicago":"Brighi, Pietro, Marko Ljubotina, Dmitry A. Abanin, and Maksym Serbyn. “Many-Body Localization Proximity Effect in a Two-Species Bosonic Hubbard Model.” <i>Physical Review B</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/physrevb.108.054201\">https://doi.org/10.1103/physrevb.108.054201</a>.","ama":"Brighi P, Ljubotina M, Abanin DA, Serbyn M. Many-body localization proximity effect in a two-species bosonic Hubbard model. <i>Physical Review B</i>. 2023;108(5). doi:<a href=\"https://doi.org/10.1103/physrevb.108.054201\">10.1103/physrevb.108.054201</a>","apa":"Brighi, P., Ljubotina, M., Abanin, D. A., &#38; Serbyn, M. (2023). Many-body localization proximity effect in a two-species bosonic Hubbard model. <i>Physical Review B</i>. American Physical Society. <a href=\"https://doi.org/10.1103/physrevb.108.054201\">https://doi.org/10.1103/physrevb.108.054201</a>","short":"P. Brighi, M. Ljubotina, D.A. Abanin, M. Serbyn, Physical Review B 108 (2023)."},"date_published":"2023-08-01T00:00:00Z","year":"2023","article_number":"054201","title":"Many-body localization proximity effect in a two-species bosonic Hubbard model","month":"08","department":[{"_id":"MaSe"}],"date_updated":"2025-04-14T07:52:06Z","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"language":[{"iso":"eng"}],"publication":"Physical Review B","has_accepted_license":"1","date_created":"2023-08-05T18:25:22Z","scopus_import":"1","status":"public","intvolume":"       108","ddc":["530"],"file":[{"content_type":"application/pdf","file_name":"2023_PhysRevB_Brighi.pdf","date_updated":"2023-08-07T09:48:08Z","file_id":"13981","creator":"dernst","checksum":"f763000339b5fd543c14377109920690","date_created":"2023-08-07T09:48:08Z","relation":"main_file","file_size":3051398,"access_level":"open_access","success":1}],"arxiv":1,"_id":"13963","oa":1,"type":"journal_article","author":[{"full_name":"Brighi, Pietro","id":"4115AF5C-F248-11E8-B48F-1D18A9856A87","last_name":"Brighi","orcid":"0000-0002-7969-2729","first_name":"Pietro"},{"first_name":"Marko","orcid":"0000-0003-0038-7068","id":"F75EE9BE-5C90-11EA-905D-16643DDC885E","full_name":"Ljubotina, Marko","last_name":"Ljubotina"},{"first_name":"Dmitry A.","last_name":"Abanin","full_name":"Abanin, Dmitry A."},{"last_name":"Serbyn","full_name":"Serbyn, Maksym","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-2399-5827","first_name":"Maksym"}],"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"We thank A. A. Michailidis and A. Mirlin for insightful discussions. P.B., M.L., and M.S. acknowledge support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 850899). D.A. was\r\nsupported by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 864597) and by the Swiss National Science Foundation. P.B., M.L., and M.S. acknowledge PRACE for awarding us access to Joliot-Curie at GENCI@CEA, France, where the TEBD simulations were performed. The TEBD simulations were performed using the ITensor library [60].","issue":"5","corr_author":"1","file_date_updated":"2023-08-07T09:48:08Z"},{"intvolume":"       108","publication":"Physical Review B","language":[{"iso":"eng"}],"date_created":"2023-09-12T07:12:12Z","scopus_import":"1","status":"public","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"A.F.Y. acknowledges primary support from the Department of Energy under award DE-SC0020043, and additional support from the Gordon and Betty Moore Foundation under award GBMF9471 for group operations.","author":[{"id":"13C09E74-18D9-11E9-8878-32CFE5697425","full_name":"Henderson, Paul M","last_name":"Henderson","orcid":"0000-0002-5198-7445","first_name":"Paul M"},{"orcid":"0000-0001-9666-3543","first_name":"Areg","last_name":"Ghazaryan","id":"4AF46FD6-F248-11E8-B48F-1D18A9856A87","full_name":"Ghazaryan, Areg"},{"first_name":"Alexander A.","full_name":"Zibrov, Alexander A.","last_name":"Zibrov"},{"last_name":"Young","full_name":"Young, Andrea F.","first_name":"Andrea F."},{"first_name":"Maksym","orcid":"0000-0002-2399-5827","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn"}],"type":"journal_article","issue":"12","arxiv":1,"_id":"14320","oa":1,"article_type":"original","main_file_link":[{"open_access":"1","url":"https://doi.org/10.48550/arXiv.2210.06310"}],"abstract":[{"text":"The development of two-dimensional materials has resulted in a diverse range of novel, high-quality compounds with increasing complexity. A key requirement for a comprehensive quantitative theory is the accurate determination of these materials' band structure parameters. However, this task is challenging due to the intricate band structures and the indirect nature of experimental probes. In this work, we introduce a general framework to derive band structure parameters from experimental data using deep neural networks. We applied our method to the penetration field capacitance measurement of trilayer graphene, an effective probe of its density of states. First, we demonstrate that a trained deep network gives accurate predictions for the penetration field capacitance as a function of tight-binding parameters. Next, we use the fast and accurate predictions from the trained network to automatically determine tight-binding parameters directly from experimental data, with extracted parameters being in a good agreement with values in the literature. We conclude by discussing potential applications of our method to other materials and experimental techniques beyond penetration field capacitance.","lang":"eng"}],"external_id":{"arxiv":["2210.06310"]},"quality_controlled":"1","day":"15","oa_version":"Preprint","volume":108,"article_number":"125411","title":"Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene","date_updated":"2023-09-20T09:38:24Z","month":"09","department":[{"_id":"MaSe"},{"_id":"ChLa"},{"_id":"MiLe"}],"publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"publisher":"American Physical Society","article_processing_charge":"No","doi":"10.1103/physrevb.108.125411","publication_status":"published","year":"2023","date_published":"2023-09-15T00:00:00Z","citation":{"ista":"Henderson PM, Ghazaryan A, Zibrov AA, Young AF, Serbyn M. 2023. Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene. Physical Review B. 108(12), 125411.","mla":"Henderson, Paul M., et al. “Deep Learning Extraction of Band Structure Parameters from Density of States: A Case Study on Trilayer Graphene.” <i>Physical Review B</i>, vol. 108, no. 12, 125411, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/physrevb.108.125411\">10.1103/physrevb.108.125411</a>.","ieee":"P. M. Henderson, A. Ghazaryan, A. A. Zibrov, A. F. Young, and M. Serbyn, “Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene,” <i>Physical Review B</i>, vol. 108, no. 12. American Physical Society, 2023.","apa":"Henderson, P. M., Ghazaryan, A., Zibrov, A. A., Young, A. F., &#38; Serbyn, M. (2023). Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene. <i>Physical Review B</i>. American Physical Society. <a href=\"https://doi.org/10.1103/physrevb.108.125411\">https://doi.org/10.1103/physrevb.108.125411</a>","short":"P.M. Henderson, A. Ghazaryan, A.A. Zibrov, A.F. Young, M. Serbyn, Physical Review B 108 (2023).","chicago":"Henderson, Paul M, Areg Ghazaryan, Alexander A. Zibrov, Andrea F. Young, and Maksym Serbyn. “Deep Learning Extraction of Band Structure Parameters from Density of States: A Case Study on Trilayer Graphene.” <i>Physical Review B</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/physrevb.108.125411\">https://doi.org/10.1103/physrevb.108.125411</a>.","ama":"Henderson PM, Ghazaryan A, Zibrov AA, Young AF, Serbyn M. Deep learning extraction of band structure parameters from density of states: A case study on trilayer graphene. <i>Physical Review B</i>. 2023;108(12). doi:<a href=\"https://doi.org/10.1103/physrevb.108.125411\">10.1103/physrevb.108.125411</a>"}},{"issue":"3","corr_author":"1","file_date_updated":"2023-09-20T10:46:10Z","type":"journal_article","acknowledgement":"We would like to thank Raimel A. Medina, Hansveer Singh, and Dmitry Abanin for useful\r\ndiscussions.The authors acknowledge support by the European Research Council\r\n(ERC) under the European Union’s Horizon 2020 research and innovation program (Grant\r\nAgreement No. 850899). We acknowledge support by the Erwin Schrödinger International\r\nInstitute for Mathematics and Physics (ESI).","author":[{"full_name":"Brighi, Pietro","id":"4115AF5C-F248-11E8-B48F-1D18A9856A87","last_name":"Brighi","first_name":"Pietro","orcid":"0000-0002-7969-2729"},{"first_name":"Marko","orcid":"0000-0003-0038-7068","full_name":"Ljubotina, Marko","id":"F75EE9BE-5C90-11EA-905D-16643DDC885E","last_name":"Ljubotina"},{"last_name":"Serbyn","full_name":"Serbyn, Maksym","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","first_name":"Maksym","orcid":"0000-0002-2399-5827"}],"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","related_material":{"record":[{"relation":"earlier_version","status":"public","id":"12750"}]},"oa":1,"arxiv":1,"_id":"14334","ddc":["530"],"file":[{"file_id":"14350","creator":"dernst","file_name":"2023_SciPostPhysics_Brighi.pdf","date_updated":"2023-09-20T10:46:10Z","content_type":"application/pdf","access_level":"open_access","success":1,"relation":"main_file","file_size":4866506,"date_created":"2023-09-20T10:46:10Z","checksum":"4cef6a8021f6b6c47ab2f2f2b1387ac2"}],"intvolume":"        15","status":"public","scopus_import":"1","keyword":["General Physics and Astronomy"],"date_created":"2023-09-14T13:08:23Z","language":[{"iso":"eng"}],"publication":"SciPost Physics","has_accepted_license":"1","month":"09","department":[{"_id":"MaSe"}],"date_updated":"2025-04-14T07:52:05Z","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"article_number":"093","title":"Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models","citation":{"ama":"Brighi P, Ljubotina M, Serbyn M. Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models. <i>SciPost Physics</i>. 2023;15(3). doi:<a href=\"https://doi.org/10.21468/scipostphys.15.3.093\">10.21468/scipostphys.15.3.093</a>","chicago":"Brighi, Pietro, Marko Ljubotina, and Maksym Serbyn. “Hilbert Space Fragmentation and Slow Dynamics in Particle-Conserving Quantum East Models.” <i>SciPost Physics</i>. SciPost Foundation, 2023. <a href=\"https://doi.org/10.21468/scipostphys.15.3.093\">https://doi.org/10.21468/scipostphys.15.3.093</a>.","short":"P. Brighi, M. Ljubotina, M. Serbyn, SciPost Physics 15 (2023).","apa":"Brighi, P., Ljubotina, M., &#38; Serbyn, M. (2023). Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models. <i>SciPost Physics</i>. SciPost Foundation. <a href=\"https://doi.org/10.21468/scipostphys.15.3.093\">https://doi.org/10.21468/scipostphys.15.3.093</a>","ieee":"P. Brighi, M. Ljubotina, and M. Serbyn, “Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models,” <i>SciPost Physics</i>, vol. 15, no. 3. SciPost Foundation, 2023.","mla":"Brighi, Pietro, et al. “Hilbert Space Fragmentation and Slow Dynamics in Particle-Conserving Quantum East Models.” <i>SciPost Physics</i>, vol. 15, no. 3, 093, SciPost Foundation, 2023, doi:<a href=\"https://doi.org/10.21468/scipostphys.15.3.093\">10.21468/scipostphys.15.3.093</a>.","ista":"Brighi P, Ljubotina M, Serbyn M. 2023. Hilbert space fragmentation and slow dynamics in particle-conserving quantum East models. SciPost Physics. 15(3), 093."},"year":"2023","date_published":"2023-09-13T00:00:00Z","doi":"10.21468/scipostphys.15.3.093","publication_identifier":{"issn":["2542-4653"]},"publisher":"SciPost Foundation","article_processing_charge":"No","publication_status":"published","article_type":"original","abstract":[{"text":"Quantum kinetically constrained models have recently attracted significant attention due to their anomalous dynamics and thermalization. In this work, we introduce a hitherto unexplored family of kinetically constrained models featuring conserved particle number and strong inversion-symmetry breaking due to facilitated hopping. We demonstrate that these models provide a generic example of so-called quantum Hilbert space fragmentation, that is manifested in disconnected sectors in the Hilbert space that are not apparent in the computational basis. Quantum Hilbert space fragmentation leads to an exponential in system size number of eigenstates with exactly zero entanglement entropy across several bipartite cuts. These eigenstates can be probed dynamically using quenches from simple initial product states. In addition, we study the particle spreading under unitary dynamics launched from the domain wall state, and find faster than diffusive dynamics at high particle densities, that crosses over into logarithmically slow relaxation at smaller densities. Using a classically simulable cellular automaton, we reproduce the logarithmic dynamics observed in the quantum case. Our work suggests that particle conserving constrained models with inversion symmetry breaking realize so far unexplored dynamical behavior and invite their further theoretical and experimental studies.","lang":"eng"}],"ec_funded":1,"oa_version":"Published Version","volume":15,"day":"13","project":[{"grant_number":"850899","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control"}],"external_id":{"arxiv":["2210.15607"]},"quality_controlled":"1"},{"quality_controlled":"1","external_id":{"arxiv":["2306.09455"],"isi":["001186160100001"]},"day":"01","oa_version":"Preprint","volume":108,"main_file_link":[{"open_access":"1","url":"https://doi.org/10.48550/arXiv.2306.09455"}],"abstract":[{"text":"Recently, a concept of generalized multifractality, which characterizes fluctuations and correlations of critical eigenstates, was introduced and explored for all 10 symmetry classes of disordered systems. Here, by using the nonlinear sigma-model (\r\nNL\r\nσ\r\nM\r\n) field theory, we extend the theory of generalized multifractality to boundaries of systems at criticality. Our numerical simulations on two-dimensional systems of symmetry classes A, C, and AII fully confirm the analytical predictions of pure-scaling observables and Weyl symmetry relations between critical exponents of surface generalized multifractality. This demonstrates the validity of the \r\nNL\r\nσ\r\nM\r\n for the description of Anderson-localization critical phenomena, not only in the bulk but also on the boundary. The critical exponents strongly violate generalized parabolicity, in analogy with earlier results for the bulk, corroborating the conclusion that the considered Anderson-localization critical points are not described by conformal field theories. We further derive relations between generalized surface multifractal spectra and linear combinations of Lyapunov exponents of a strip in quasi-one-dimensional geometry, which hold under the assumption of invariance with respect to a logarithmic conformal map. Our numerics demonstrate that these relations hold with an excellent accuracy. Taken together, our results indicate an intriguing situation: the conformal invariance is broken but holds partially at critical points of Anderson localization.","lang":"eng"}],"article_type":"original","publication_status":"published","doi":"10.1103/PhysRevB.108.104205","article_processing_charge":"No","publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"publisher":"American Physical Society","citation":{"ista":"Babkin S, Karcher JF, Burmistrov IS, Mirlin AD. 2023. Generalized surface multifractality in two-dimensional disordered systems. Physical Review B. 108(10), 104205.","ieee":"S. Babkin, J. F. Karcher, I. S. Burmistrov, and A. D. Mirlin, “Generalized surface multifractality in two-dimensional disordered systems,” <i>Physical Review B</i>, vol. 108, no. 10. American Physical Society, 2023.","mla":"Babkin, Serafim, et al. “Generalized Surface Multifractality in Two-Dimensional Disordered Systems.” <i>Physical Review B</i>, vol. 108, no. 10, 104205, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/PhysRevB.108.104205\">10.1103/PhysRevB.108.104205</a>.","short":"S. Babkin, J.F. Karcher, I.S. Burmistrov, A.D. Mirlin, Physical Review B 108 (2023).","apa":"Babkin, S., Karcher, J. F., Burmistrov, I. S., &#38; Mirlin, A. D. (2023). Generalized surface multifractality in two-dimensional disordered systems. <i>Physical Review B</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevB.108.104205\">https://doi.org/10.1103/PhysRevB.108.104205</a>","ama":"Babkin S, Karcher JF, Burmistrov IS, Mirlin AD. Generalized surface multifractality in two-dimensional disordered systems. <i>Physical Review B</i>. 2023;108(10). doi:<a href=\"https://doi.org/10.1103/PhysRevB.108.104205\">10.1103/PhysRevB.108.104205</a>","chicago":"Babkin, Serafim, Jonas F. Karcher, Igor S. Burmistrov, and Alexander D. Mirlin. “Generalized Surface Multifractality in Two-Dimensional Disordered Systems.” <i>Physical Review B</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/PhysRevB.108.104205\">https://doi.org/10.1103/PhysRevB.108.104205</a>."},"year":"2023","date_published":"2023-09-01T00:00:00Z","title":"Generalized surface multifractality in two-dimensional disordered systems","article_number":"104205","isi":1,"month":"09","department":[{"_id":"MaSe"}],"date_updated":"2025-09-09T13:03:44Z","language":[{"iso":"eng"}],"publication":"Physical Review B","date_created":"2023-10-08T22:01:17Z","scopus_import":"1","status":"public","intvolume":"       108","_id":"14406","arxiv":1,"oa":1,"type":"journal_article","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","author":[{"first_name":"Serafim","orcid":"0009-0003-7382-8036","id":"41e64307-6672-11ee-b9ad-cc7a0075a479","full_name":"Babkin, Serafim","last_name":"Babkin"},{"full_name":"Karcher, Jonas F.","last_name":"Karcher","first_name":"Jonas F."},{"first_name":"Igor S.","full_name":"Burmistrov, Igor S.","last_name":"Burmistrov"},{"last_name":"Mirlin","full_name":"Mirlin, Alexander D.","first_name":"Alexander D."}],"acknowledgement":"We thank Ilya Gruzberg for many illuminating discussions. S.S.B., J.F.K., and A.D.M. acknowledge support by the Deutsche Forschungsgemeinschaft (DFG) via the Grant\r\nNo. MI 658/14-1. I.S.B. acknowledges support from Russian Science Foundation (Grant No. 22-42-04416).","issue":"10"},{"scopus_import":"1","status":"public","date_created":"2023-12-17T23:00:53Z","language":[{"iso":"eng"}],"publication":"Physical Review B","intvolume":"       108","oa":1,"_id":"14690","arxiv":1,"issue":"20","corr_author":"1","type":"journal_article","user_id":"317138e5-6ab7-11ef-aa6d-ffef3953e345","author":[{"orcid":"0009-0003-7382-8036","first_name":"Serafim","last_name":"Babkin","full_name":"Babkin, Serafim","id":"41e64307-6672-11ee-b9ad-cc7a0075a479"},{"full_name":"Burmistrov, I","last_name":"Burmistrov","first_name":"I"}],"acknowledgement":"The authors are grateful to J. Karcher and A. Mirlin for collaboration on the related project. We thank I. Gruzberg and A. Mirlin for useful discussions and comments. I.S.B. is grateful to M. Parfenov and P. Ostrovsky for collaboration on the related project. The research was supported by Russian Science Foundation (Grant No. 22-42-04416).","day":"15","oa_version":"Preprint","volume":108,"external_id":{"arxiv":["2308.16852"],"isi":["001141678200003"]},"quality_controlled":"1","abstract":[{"text":"Generalized multifractality characterizes system size dependence of pure scaling local observables at Anderson transitions in all 10 symmetry classes of disordered systems. Recently, the concept of generalized multifractality has been extended to boundaries of critical disordered noninteracting systems. Here we study the generalized boundary multifractality in the presence of electron-electron interaction, focusing on the spin quantum Hall symmetry class (class C). Employing the two-loop renormalization group analysis within the Finkel'stein nonlinear sigma model, we compute the anomalous dimensions of the pure scaling operators located at the boundary of the system. We find that generalized boundary multifractal exponents are twice larger than their bulk counterparts. Exact symmetry relations between generalized boundary multifractal exponents in the case of noninteracting systems are explicitly broken by the interaction.","lang":"eng"}],"main_file_link":[{"url":" https://doi.org/10.48550/arXiv.2308.16852","open_access":"1"}],"article_type":"original","citation":{"apa":"Babkin, S., &#38; Burmistrov, I. (2023). Boundary multifractality in the spin quantum Hall symmetry class with interaction. <i>Physical Review B</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevB.108.205429\">https://doi.org/10.1103/PhysRevB.108.205429</a>","short":"S. Babkin, I. Burmistrov, Physical Review B 108 (2023).","chicago":"Babkin, Serafim, and I Burmistrov. “Boundary Multifractality in the Spin Quantum Hall Symmetry Class with Interaction.” <i>Physical Review B</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/PhysRevB.108.205429\">https://doi.org/10.1103/PhysRevB.108.205429</a>.","ama":"Babkin S, Burmistrov I. Boundary multifractality in the spin quantum Hall symmetry class with interaction. <i>Physical Review B</i>. 2023;108(20). doi:<a href=\"https://doi.org/10.1103/PhysRevB.108.205429\">10.1103/PhysRevB.108.205429</a>","ista":"Babkin S, Burmistrov I. 2023. Boundary multifractality in the spin quantum Hall symmetry class with interaction. Physical Review B. 108(20), 205429.","mla":"Babkin, Serafim, and I. Burmistrov. “Boundary Multifractality in the Spin Quantum Hall Symmetry Class with Interaction.” <i>Physical Review B</i>, vol. 108, no. 20, 205429, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/PhysRevB.108.205429\">10.1103/PhysRevB.108.205429</a>.","ieee":"S. Babkin and I. Burmistrov, “Boundary multifractality in the spin quantum Hall symmetry class with interaction,” <i>Physical Review B</i>, vol. 108, no. 20. American Physical Society, 2023."},"year":"2023","date_published":"2023-11-15T00:00:00Z","publication_status":"published","doi":"10.1103/PhysRevB.108.205429","publication_identifier":{"issn":["2469-9950"],"eissn":["2469-9969"]},"article_processing_charge":"No","publisher":"American Physical Society","department":[{"_id":"MaSe"}],"month":"11","date_updated":"2025-09-09T14:00:09Z","title":"Boundary multifractality in the spin quantum Hall symmetry class with interaction","isi":1,"article_number":"205429"},{"volume":107,"day":"01","oa_version":"Preprint","quality_controlled":"1","external_id":{"arxiv":["2211.02492"],"isi":["000945526400003"]},"article_type":"original","abstract":[{"text":"Motivated by the recent discoveries of superconductivity in bilayer and trilayer graphene, we theoretically investigate superconductivity and other interaction-driven phases in multilayer graphene stacks. To this end, we study the density of states of multilayer graphene with up to four layers at the single-particle band structure level in the presence of a transverse electric field. Among the considered structures, tetralayer graphene with rhombohedral (ABCA) stacking reaches the highest density of states. We study the phases that can arise in ABCA graphene by tuning the carrier density and transverse electric field. For a broad region of the tuning parameters, the presence of strong Coulomb repulsion leads to a spontaneous spin and valley symmetry breaking via Stoner transitions. Using a model that incorporates the spontaneous spin and valley polarization, we explore the Kohn-Luttinger mechanism for superconductivity driven by repulsive Coulomb interactions. We find that the strongest superconducting instability is in the p-wave channel, and occurs in proximity to the onset of Stoner transitions. Interestingly, we find a range of densities and transverse electric fields where superconductivity develops out of a strongly corrugated, singly connected Fermi surface in each valley, leading to a topologically nontrivial chiral p+ip superconducting state with an even number of copropagating chiral Majorana edge modes. Our work establishes ABCA-stacked tetralayer graphene as a promising platform for observing strongly correlated physics and topological superconductivity.","lang":"eng"}],"main_file_link":[{"open_access":"1","url":"https://doi.org/10.48550/arXiv.2211.02492"}],"date_published":"2023-03-01T00:00:00Z","year":"2023","citation":{"apa":"Ghazaryan, A., Holder, T., Berg, E., &#38; Serbyn, M. (2023). Multilayer graphenes as a platform for interaction-driven physics and topological superconductivity. <i>Physical Review B</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevB.107.104502\">https://doi.org/10.1103/PhysRevB.107.104502</a>","short":"A. Ghazaryan, T. Holder, E. Berg, M. Serbyn, Physical Review B 107 (2023).","chicago":"Ghazaryan, Areg, Tobias Holder, Erez Berg, and Maksym Serbyn. “Multilayer Graphenes as a Platform for Interaction-Driven Physics and Topological Superconductivity.” <i>Physical Review B</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/PhysRevB.107.104502\">https://doi.org/10.1103/PhysRevB.107.104502</a>.","ama":"Ghazaryan A, Holder T, Berg E, Serbyn M. Multilayer graphenes as a platform for interaction-driven physics and topological superconductivity. <i>Physical Review B</i>. 2023;107(10). doi:<a href=\"https://doi.org/10.1103/PhysRevB.107.104502\">10.1103/PhysRevB.107.104502</a>","ista":"Ghazaryan A, Holder T, Berg E, Serbyn M. 2023. Multilayer graphenes as a platform for interaction-driven physics and topological superconductivity. Physical Review B. 107(10), 104502.","mla":"Ghazaryan, Areg, et al. “Multilayer Graphenes as a Platform for Interaction-Driven Physics and Topological Superconductivity.” <i>Physical Review B</i>, vol. 107, no. 10, 104502, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/PhysRevB.107.104502\">10.1103/PhysRevB.107.104502</a>.","ieee":"A. Ghazaryan, T. Holder, E. Berg, and M. Serbyn, “Multilayer graphenes as a platform for interaction-driven physics and topological superconductivity,” <i>Physical Review B</i>, vol. 107, no. 10. American Physical Society, 2023."},"publication_identifier":{"eissn":["2469-9969"],"issn":["2469-9950"]},"article_processing_charge":"No","publisher":"American Physical Society","doi":"10.1103/PhysRevB.107.104502","publication_status":"published","date_updated":"2023-08-01T13:59:29Z","month":"03","department":[{"_id":"MaSe"},{"_id":"MiLe"}],"article_number":"104502","isi":1,"title":"Multilayer graphenes as a platform for interaction-driven physics and topological superconductivity","date_created":"2023-04-02T22:01:10Z","status":"public","scopus_import":"1","publication":"Physical Review B","language":[{"iso":"eng"}],"intvolume":"       107","oa":1,"related_material":{"link":[{"relation":"press_release","url":"https://ista.ac.at/en/news/reaching-superconductivity-layer-by-layer/","description":"News on the ISTA website"}]},"arxiv":1,"_id":"12790","issue":"10","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","acknowledgement":"E.B. and T.H. were supported by the European Research Council (ERC) under grant HQMAT (Grant Agreement No. 817799), by the Israel-USA Binational Science Foundation (BSF), and by a Research grant from Irving and Cherna Moskowitz.","author":[{"id":"4AF46FD6-F248-11E8-B48F-1D18A9856A87","full_name":"Ghazaryan, Areg","last_name":"Ghazaryan","orcid":"0000-0001-9666-3543","first_name":"Areg"},{"first_name":"Tobias","last_name":"Holder","full_name":"Holder, Tobias"},{"full_name":"Berg, Erez","last_name":"Berg","first_name":"Erez"},{"id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn","first_name":"Maksym","orcid":"0000-0002-2399-5827"}],"type":"journal_article"},{"scopus_import":"1","status":"public","date_created":"2023-04-16T22:01:09Z","has_accepted_license":"1","publication":"Physical Review X","language":[{"iso":"eng"}],"file":[{"checksum":"ee060cea609af79bba7af74b1ce28078","date_created":"2023-04-17T08:36:53Z","relation":"main_file","file_size":1958523,"success":1,"access_level":"open_access","content_type":"application/pdf","file_name":"2023_PhysReviewX_Ljubotina.pdf","date_updated":"2023-04-17T08:36:53Z","creator":"dernst","file_id":"12845"}],"ddc":["530"],"intvolume":"        13","oa":1,"_id":"12839","file_date_updated":"2023-04-17T08:36:53Z","corr_author":"1","issue":"1","acknowledgement":"We would like to thank Alexios Michailidis, Sarang Gopalakrishnan, and Achilleas Lazarides for useful comments. M. L. and M. S. acknowledge support by the European Research Council under the European Union’s Horizon 2020 research and innovation program (Grant\r\nAgreement No. 850899). J.-Y. D. and Z. P. acknowledge support by EPSRC Grant No. EP/R513258/1 and the Leverhulme Trust Research Leadership Grant No. RL2019-015. Statement of compliance with EPSRC policy framework on research data: This publication is theoretical work that does not require supporting research data. M. S., M. L., and Z. P. acknowledge support by the Erwin Schrödinger International Institute for Mathematics and\r\nPhysics. M. L. and M. S. acknowledge PRACE for awarding us access to Joliot-Curie at GENCI@CEA, France, where the TEBD simulations were performed. The TEBD\r\nsimulations were performed using the ITENSOR library [54].","author":[{"last_name":"Ljubotina","full_name":"Ljubotina, Marko","id":"F75EE9BE-5C90-11EA-905D-16643DDC885E","first_name":"Marko","orcid":"0000-0003-0038-7068"},{"full_name":"Desaules, Jean Yves","last_name":"Desaules","first_name":"Jean Yves"},{"id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn","first_name":"Maksym","orcid":"0000-0002-2399-5827"},{"first_name":"Zlatko","last_name":"Papić","full_name":"Papić, Zlatko"}],"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","type":"journal_article","oa_version":"Published Version","volume":13,"day":"07","ec_funded":1,"external_id":{"isi":["000957625700001"]},"quality_controlled":"1","project":[{"_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","call_identifier":"H2020","grant_number":"850899"}],"abstract":[{"text":"Universal nonequilibrium properties of isolated quantum systems are typically probed by studying transport of conserved quantities, such as charge or spin, while transport of energy has received considerably less attention. Here, we study infinite-temperature energy transport in the kinetically constrained PXP model describing Rydberg atom quantum simulators. Our state-of-the-art numerical simulations, including exact diagonalization and time-evolving block decimation methods, reveal the existence of two distinct transport regimes. At moderate times, the energy-energy correlation function displays periodic oscillations due to families of eigenstates forming different su(2) representations hidden within the spectrum. These families of eigenstates generalize the quantum many-body scarred states found in previous works and leave an imprint on the infinite-temperature energy transport. At later times, we observe a long-lived superdiffusive transport regime that we attribute to the proximity of a nearby integrable point. While generic strong deformations of the PXP model indeed restore diffusive transport, adding a strong chemical potential intriguingly gives rise to a well-converged superdiffusive exponent z≈3/2. Our results suggest constrained models to be potential hosts of novel transport regimes and call for developing an analytic understanding of their energy transport.","lang":"eng"}],"article_type":"original","year":"2023","date_published":"2023-03-07T00:00:00Z","citation":{"ama":"Ljubotina M, Desaules JY, Serbyn M, Papić Z. Superdiffusive energy transport in kinetically constrained models. <i>Physical Review X</i>. 2023;13(1). doi:<a href=\"https://doi.org/10.1103/PhysRevX.13.011033\">10.1103/PhysRevX.13.011033</a>","chicago":"Ljubotina, Marko, Jean Yves Desaules, Maksym Serbyn, and Zlatko Papić. “Superdiffusive Energy Transport in Kinetically Constrained Models.” <i>Physical Review X</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/PhysRevX.13.011033\">https://doi.org/10.1103/PhysRevX.13.011033</a>.","short":"M. Ljubotina, J.Y. Desaules, M. Serbyn, Z. Papić, Physical Review X 13 (2023).","apa":"Ljubotina, M., Desaules, J. Y., Serbyn, M., &#38; Papić, Z. (2023). Superdiffusive energy transport in kinetically constrained models. <i>Physical Review X</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevX.13.011033\">https://doi.org/10.1103/PhysRevX.13.011033</a>","ieee":"M. Ljubotina, J. Y. Desaules, M. Serbyn, and Z. Papić, “Superdiffusive energy transport in kinetically constrained models,” <i>Physical Review X</i>, vol. 13, no. 1. American Physical Society, 2023.","mla":"Ljubotina, Marko, et al. “Superdiffusive Energy Transport in Kinetically Constrained Models.” <i>Physical Review X</i>, vol. 13, no. 1, 011033, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/PhysRevX.13.011033\">10.1103/PhysRevX.13.011033</a>.","ista":"Ljubotina M, Desaules JY, Serbyn M, Papić Z. 2023. Superdiffusive energy transport in kinetically constrained models. Physical Review X. 13(1), 011033."},"publication_status":"published","article_processing_charge":"No","publisher":"American Physical Society","publication_identifier":{"eissn":["2160-3308"]},"doi":"10.1103/PhysRevX.13.011033","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"date_updated":"2025-04-14T07:52:07Z","department":[{"_id":"MaSe"}],"month":"03","title":"Superdiffusive energy transport in kinetically constrained models","isi":1,"article_number":"011033"},{"article_type":"original","abstract":[{"lang":"eng","text":"Recent experimental advances have inspired the development of theoretical tools to describe the non-equilibrium dynamics of quantum systems. Among them an exact representation of quantum spin systems in terms of classical stochastic processes has been proposed. Here we provide first steps towards the extension of this stochastic approach to bosonic systems by considering the one-dimensional quantum quartic oscillator. We show how to exactly parameterize the time evolution of this prototypical model via the dynamics of a set of classical variables. We interpret these variables as stochastic processes, which allows us to propose a novel way to numerically simulate the time evolution of the system. We benchmark our findings by considering analytically solvable limits and providing alternative derivations of known results."}],"ec_funded":1,"volume":6,"oa_version":"Published Version","day":"14","external_id":{"arxiv":["2211.01923"]},"quality_controlled":"1","project":[{"grant_number":"754411","call_identifier":"H2020","name":"ISTplus - Postdoctoral Fellowships","_id":"260C2330-B435-11E9-9278-68D0E5697425"}],"date_updated":"2025-04-14T07:43:56Z","department":[{"_id":"MaSe"}],"month":"04","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"article_number":"029","title":"Stochastic representation of the quantum quartic oscillator","year":"2023","date_published":"2023-04-14T00:00:00Z","citation":{"ama":"Tucci G, De Nicola S, Wald S, Gambassi A. Stochastic representation of the quantum quartic oscillator. <i>SciPost Physics Core</i>. 2023;6(2). doi:<a href=\"https://doi.org/10.21468/scipostphyscore.6.2.029\">10.21468/scipostphyscore.6.2.029</a>","chicago":"Tucci, Gennaro, Stefano De Nicola, Sascha Wald, and Andrea Gambassi. “Stochastic Representation of the Quantum Quartic Oscillator.” <i>SciPost Physics Core</i>. SciPost Foundation, 2023. <a href=\"https://doi.org/10.21468/scipostphyscore.6.2.029\">https://doi.org/10.21468/scipostphyscore.6.2.029</a>.","short":"G. Tucci, S. De Nicola, S. Wald, A. Gambassi, SciPost Physics Core 6 (2023).","apa":"Tucci, G., De Nicola, S., Wald, S., &#38; Gambassi, A. (2023). Stochastic representation of the quantum quartic oscillator. <i>SciPost Physics Core</i>. SciPost Foundation. <a href=\"https://doi.org/10.21468/scipostphyscore.6.2.029\">https://doi.org/10.21468/scipostphyscore.6.2.029</a>","ieee":"G. Tucci, S. De Nicola, S. Wald, and A. Gambassi, “Stochastic representation of the quantum quartic oscillator,” <i>SciPost Physics Core</i>, vol. 6, no. 2. SciPost Foundation, 2023.","mla":"Tucci, Gennaro, et al. “Stochastic Representation of the Quantum Quartic Oscillator.” <i>SciPost Physics Core</i>, vol. 6, no. 2, 029, SciPost Foundation, 2023, doi:<a href=\"https://doi.org/10.21468/scipostphyscore.6.2.029\">10.21468/scipostphyscore.6.2.029</a>.","ista":"Tucci G, De Nicola S, Wald S, Gambassi A. 2023. Stochastic representation of the quantum quartic oscillator. SciPost Physics Core. 6(2), 029."},"article_processing_charge":"No","publication_identifier":{"issn":["2666-9366"]},"publisher":"SciPost Foundation","doi":"10.21468/scipostphyscore.6.2.029","publication_status":"published","ddc":["530"],"file":[{"file_id":"13329","creator":"dernst","file_name":"2023_SciPostPhysCore_Tucci.pdf","date_updated":"2023-07-31T09:02:27Z","content_type":"application/pdf","success":1,"access_level":"open_access","relation":"main_file","file_size":523236,"date_created":"2023-07-31T09:02:27Z","checksum":"b472bc82108747eda5d52adf9e2ac7f3"}],"intvolume":"         6","keyword":["Statistical and Nonlinear Physics","Atomic and Molecular Physics","and Optics","Nuclear and High Energy Physics","Condensed Matter Physics"],"scopus_import":"1","status":"public","date_created":"2023-07-24T10:47:46Z","publication":"SciPost Physics Core","language":[{"iso":"eng"}],"has_accepted_license":"1","corr_author":"1","issue":"2","file_date_updated":"2023-07-31T09:02:27Z","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"first_name":"Gennaro","full_name":"Tucci, Gennaro","last_name":"Tucci"},{"first_name":"Stefano","orcid":"0000-0002-4842-6671","id":"42832B76-F248-11E8-B48F-1D18A9856A87","full_name":"De Nicola, Stefano","last_name":"De Nicola"},{"first_name":"Sascha","full_name":"Wald, Sascha","last_name":"Wald"},{"full_name":"Gambassi, Andrea","last_name":"Gambassi","first_name":"Andrea"}],"acknowledgement":"S. De Nicola acknowledges funding from the Institute of Science and Technology Austria (ISTA), and from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant Agreement No. 754411. S. De Nicola also acknowledges funding from the EPSRC Center for Doctoral Training in Cross-Disciplinary Approaches to NonEquilibrium Systems (CANES) under Grant EP/L015854/1. ","type":"journal_article","oa":1,"arxiv":1,"_id":"13277"},{"related_material":{"record":[{"id":"12750","status":"public","relation":"part_of_dissertation"},{"status":"public","id":"11470","relation":"part_of_dissertation"},{"id":"8308","status":"public","relation":"part_of_dissertation"},{"status":"public","id":"11469","relation":"part_of_dissertation"}]},"oa":1,"_id":"12732","OA_place":"publisher","file_date_updated":"2023-03-23T16:43:14Z","corr_author":"1","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","author":[{"orcid":"0000-0002-7969-2729","first_name":"Pietro","id":"4115AF5C-F248-11E8-B48F-1D18A9856A87","full_name":"Brighi, Pietro","last_name":"Brighi"}],"type":"dissertation","supervisor":[{"last_name":"Serbyn","full_name":"Serbyn, Maksym","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0002-2399-5827","first_name":"Maksym"}],"status":"public","date_created":"2023-03-17T13:30:48Z","acknowledged_ssus":[{"_id":"ScienComp"}],"has_accepted_license":"1","language":[{"iso":"eng"}],"file":[{"content_type":"application/zip","file_name":"Thesis_sub_PBrighi.zip","date_updated":"2023-03-23T16:42:56Z","file_id":"12753","creator":"pbrighi","checksum":"5d2de651ef9449c1b8dc27148ca74777","date_created":"2023-03-23T16:42:56Z","file_size":42167561,"relation":"source_file","access_level":"closed"},{"checksum":"7caa153d4a5b0873a79358787d2dfe1e","date_created":"2023-03-23T16:43:14Z","relation":"main_file","file_size":13977000,"access_level":"open_access","success":1,"content_type":"application/pdf","date_updated":"2023-03-23T16:43:14Z","file_name":"Thesis_PBrighi.pdf","creator":"pbrighi","file_id":"12754"}],"ddc":["530"],"page":"158","date_published":"2023-03-21T00:00:00Z","year":"2023","citation":{"apa":"Brighi, P. (2023). <i>Ergodicity breaking in disordered and kinetically constrained quantum many-body systems</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:12732\">https://doi.org/10.15479/at:ista:12732</a>","short":"P. Brighi, Ergodicity Breaking in Disordered and Kinetically Constrained Quantum Many-Body Systems, Institute of Science and Technology Austria, 2023.","chicago":"Brighi, Pietro. “Ergodicity Breaking in Disordered and Kinetically Constrained Quantum Many-Body Systems.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:12732\">https://doi.org/10.15479/at:ista:12732</a>.","ama":"Brighi P. Ergodicity breaking in disordered and kinetically constrained quantum many-body systems. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:12732\">10.15479/at:ista:12732</a>","ista":"Brighi P. 2023. Ergodicity breaking in disordered and kinetically constrained quantum many-body systems. Institute of Science and Technology Austria.","mla":"Brighi, Pietro. <i>Ergodicity Breaking in Disordered and Kinetically Constrained Quantum Many-Body Systems</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:12732\">10.15479/at:ista:12732</a>.","ieee":"P. Brighi, “Ergodicity breaking in disordered and kinetically constrained quantum many-body systems,” Institute of Science and Technology Austria, 2023."},"publication_status":"published","degree_awarded":"PhD","article_processing_charge":"No","publisher":"Institute of Science and Technology Austria","publication_identifier":{"issn":["2663-337X"]},"doi":"10.15479/at:ista:12732","license":"https://creativecommons.org/licenses/by-nc-sa/4.0/","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","short":"CC BY-NC-SA (4.0)"},"date_updated":"2026-04-07T13:26:32Z","department":[{"_id":"GradSch"},{"_id":"MaSe"}],"month":"03","title":"Ergodicity breaking in disordered and kinetically constrained quantum many-body systems","day":"21","oa_version":"Published Version","ec_funded":1,"project":[{"grant_number":"850899","call_identifier":"H2020","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E"}],"alternative_title":["ISTA Thesis"],"abstract":[{"lang":"eng","text":"Nonergodic systems, whose out-of-equilibrium dynamics fail to thermalize, provide a fascinating research direction both for fundamental reasons and for application in state of the art quantum devices.\r\nGoing beyond the description of statistical mechanics, ergodicity breaking yields a new paradigm in quantum many-body physics, introducing novel phases of matter with no counterpart at equilibrium.\r\nIn this Thesis, we address different open questions in the field, focusing on disorder-induced many-body localization (MBL) and on weak ergodicity breaking in kinetically constrained models.\r\nIn particular, we contribute to the debate about transport in kinetically constrained models, studying the effect of $U(1)$ conservation and inversion-symmetry breaking in a family of quantum East models.\r\nUsing tensor network techniques, we analyze the dynamics of large MBL systems beyond the limit of exact numerical methods.\r\nIn this setting, we approach the debated topic of the coexistence of localized and thermal eigenstates separated by energy thresholds known as many-body mobility edges.\r\nInspired by recent experiments, our work further investigates the localization of a small bath induced by the coupling to a large localized chain, the so-called MBL proximity effect.\r\n\r\nIn the first Chapter, we introduce a family of particle-conserving kinetically constrained models, inspired by the quantum East model.\r\nThe system we study features strong inversion-symmetry breaking, due to the nature of the correlated hopping.\r\nWe show that these models host so-called quantum Hilbert space fragmentation, consisting of disconnected subsectors in an entangled basis, and further provide an analytical description of this phenomenon.\r\nWe further probe its effect on dynamics of simple product states, showing revivals in fidelity and local observalbes.\r\nThe study of dynamics within the largest subsector reveals an anomalous transient superdiffusive behavior crossing over to slow logarithmic dynamics at later times.\r\nThis work suggests that particle conserving constrained models with inversion-symmetry breaking realize new universality classes of dynamics and invite their further theoretical and experimental studies.\r\n\r\nNext, we use kinetic constraints and disorder to design a model with many-body mobility edges in particle density.\r\nThis feature allows to study the dynamics of localized and thermal states in large systems beyond the limitations of previous studies.\r\nThe time-evolution shows typical signatures of localization at small densities, replaced by thermal behavior at larger densities.\r\nOur results provide evidence in favor of the stability of many-body mobility edges, which was recently challenged by a theoretical argument.\r\nTo support our findings, we probe the mechanism proposed as a cause of delocalization in many-body localized systems with mobility edges suggesting its ineffectiveness in the model studied.\r\n\r\nIn the last Chapter of this Thesis, we address the topic of many-body localization proximity effect.\r\nWe study a model inspired by recent experiments, featuring Anderson localized coupled to a small bath of free hard-core bosons.\r\nThe interaction among the two particle species results in non-trivial dynamics, which we probe using tensor network techniques.\r\nOur simulations show convincing evidence of many-body localization proximity effect when the bath is composed by a single free particle and interactions are strong.\r\nWe furthter observe an anomalous entanglement dynamics, which we explain through a phenomenological theory.\r\nFinally, we extract highly excited eigenstates of large systems, providing supplementary evidence in favor of our findings."}]},{"file":[{"creator":"ssack","file_id":"14635","date_updated":"2024-11-30T23:30:03Z","file_name":"PhD_Thesis.pdf","embargo":"2024-11-30","content_type":"application/pdf","access_level":"open_access","relation":"main_file","file_size":11947523,"date_created":"2023-11-30T15:53:10Z","checksum":"068fd3570506ec42b2faa390de784bc4"},{"date_created":"2023-11-30T15:54:11Z","checksum":"0fa3bc0d108aed0ac59d2c6beef2220a","access_level":"closed","file_size":18422964,"relation":"source_file","date_updated":"2024-11-30T23:30:03Z","file_name":"PhD Thesis (1).zip","content_type":"application/zip","creator":"ssack","file_id":"14636","embargo_to":"open_access"}],"ddc":["530"],"page":"142","supervisor":[{"id":"47809E7E-F248-11E8-B48F-1D18A9856A87","full_name":"Serbyn, Maksym","last_name":"Serbyn","orcid":"0000-0002-2399-5827","first_name":"Maksym"}],"status":"public","date_created":"2023-11-28T10:58:13Z","has_accepted_license":"1","language":[{"iso":"eng"}],"file_date_updated":"2024-11-30T23:30:03Z","corr_author":"1","type":"dissertation","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","author":[{"first_name":"Stefan","orcid":"0000-0001-5400-8508","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","full_name":"Sack, Stefan","last_name":"Sack"}],"oa":1,"related_material":{"record":[{"relation":"part_of_dissertation","id":"13125","status":"public"},{"id":"11471","status":"public","relation":"part_of_dissertation"},{"status":"public","id":"9760","relation":"part_of_dissertation"}]},"OA_place":"publisher","_id":"14622","abstract":[{"text":"This Ph.D. thesis presents a detailed investigation into Variational Quantum Algorithms\r\n(VQAs), a promising class of quantum algorithms that are well suited for near-term quantum\r\ncomputation due to their moderate hardware requirements and resilience to noise. Our\r\nprimary focus lies on two particular types of VQAs: the Quantum Approximate Optimization\r\nAlgorithm (QAOA), used for solving binary optimization problems, and the Variational Quantum\r\nEigensolver (VQE), utilized for finding ground states of quantum many-body systems.\r\nIn the first part of the thesis, we examine the issue of effective parameter initialization for\r\nthe QAOA. The work demonstrates that random initialization of the QAOA often leads to\r\nconvergence in local minima with sub-optimal performance. To mitigate this issue, we propose\r\nan initialization of QAOA parameters based on the Trotterized Quantum Annealing (TQA).\r\nWe show that TQA initialization leads to the same performance as the best of an exponentially\r\nscaling number of random initializations.\r\nThe second study introduces Transition States (TS), stationary points with a single direction\r\nof descent, as a tool for systematically exploring the QAOA optimization landscape. This\r\nleads us to propose a novel greedy parameter initialization strategy that guarantees for the\r\nenergy to decrease with increasing number of circuit layers.\r\nIn the third section, we extend the QAOA to qudit systems, which are higher-dimensional\r\ngeneralizations of qubits. This chapter provides theoretical insights and practical strategies for\r\nleveraging the increased computational power of qudits in the context of quantum optimization\r\nalgorithms and suggests a quantum circuit for implementing the algorithm on an ion trap\r\nquantum computer.\r\nFinally, we propose an algorithm to avoid “barren plateaus”, regions in parameter space with\r\nvanishing gradients that obstruct efficient parameter optimization. This novel approach relies\r\non defining a notion of weak barren plateaus based on the entropies of local reduced density\r\nmatrices and showcases how these can be efficiently quantified using shadow tomography.\r\nTo illustrate the approach we employ the strategy in the VQE and show that it allows to\r\nsuccessfully avoid barren plateaus in the initialization and throughout the optimization.\r\nTaken together, this thesis greatly enhances our understanding of parameter initialization and\r\noptimization in VQAs, expands the scope of QAOA to higher-dimensional quantum systems,\r\nand presents a method to address the challenge of barren plateaus using the VQE. These\r\ninsights are instrumental in advancing the field of near-term quantum computation.","lang":"eng"}],"day":"30","oa_version":"Published Version","ec_funded":1,"project":[{"name":"IMB PhD Nomination Fellowship - Stefan Sack","_id":"bd660c93-d553-11ed-ba76-fb0fb6f49c0d"},{"name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020","grant_number":"850899"}],"alternative_title":["ISTA Thesis"],"tmp":{"legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","short":"CC BY-NC-SA (4.0)"},"department":[{"_id":"GradSch"},{"_id":"MaSe"}],"month":"11","date_updated":"2026-04-07T13:53:47Z","title":"Improving variational quantum algorithms : Innovative initialization techniques and extensions to qudit systems","citation":{"ista":"Sack S. 2023. Improving variational quantum algorithms : Innovative initialization techniques and extensions to qudit systems. Institute of Science and Technology Austria.","mla":"Sack, Stefan. <i>Improving Variational Quantum Algorithms : Innovative Initialization Techniques and Extensions to Qudit Systems</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:14622\">10.15479/at:ista:14622</a>.","ieee":"S. Sack, “Improving variational quantum algorithms : Innovative initialization techniques and extensions to qudit systems,” Institute of Science and Technology Austria, 2023.","apa":"Sack, S. (2023). <i>Improving variational quantum algorithms : Innovative initialization techniques and extensions to qudit systems</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:14622\">https://doi.org/10.15479/at:ista:14622</a>","short":"S. Sack, Improving Variational Quantum Algorithms : Innovative Initialization Techniques and Extensions to Qudit Systems, Institute of Science and Technology Austria, 2023.","chicago":"Sack, Stefan. “Improving Variational Quantum Algorithms : Innovative Initialization Techniques and Extensions to Qudit Systems.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:14622\">https://doi.org/10.15479/at:ista:14622</a>.","ama":"Sack S. Improving variational quantum algorithms : Innovative initialization techniques and extensions to qudit systems. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:14622\">10.15479/at:ista:14622</a>"},"year":"2023","date_published":"2023-11-30T00:00:00Z","degree_awarded":"PhD","publication_status":"published","doi":"10.15479/at:ista:14622","publisher":"Institute of Science and Technology Austria","article_processing_charge":"No","publication_identifier":{"issn":["2663-337X"]}},{"isi":1,"article_number":"062404","title":"Recursive greedy initialization of the quantum approximate optimization algorithm with guaranteed improvement","month":"06","department":[{"_id":"MaSe"}],"date_updated":"2026-04-22T22:30:25Z","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"doi":"10.1103/physreva.107.062404","publication_identifier":{"issn":["2469-9926"],"eissn":["2469-9934"]},"publisher":"American Physical Society","article_processing_charge":"No","publication_status":"published","citation":{"short":"S. Sack, R.A. Medina Ramos, R. Kueng, M. Serbyn, Physical Review A 107 (2023).","apa":"Sack, S., Medina Ramos, R. A., Kueng, R., &#38; Serbyn, M. (2023). Recursive greedy initialization of the quantum approximate optimization algorithm with guaranteed improvement. <i>Physical Review A</i>. American Physical Society. <a href=\"https://doi.org/10.1103/physreva.107.062404\">https://doi.org/10.1103/physreva.107.062404</a>","ama":"Sack S, Medina Ramos RA, Kueng R, Serbyn M. Recursive greedy initialization of the quantum approximate optimization algorithm with guaranteed improvement. <i>Physical Review A</i>. 2023;107(6). doi:<a href=\"https://doi.org/10.1103/physreva.107.062404\">10.1103/physreva.107.062404</a>","chicago":"Sack, Stefan, Raimel A Medina Ramos, Richard Kueng, and Maksym Serbyn. “Recursive Greedy Initialization of the Quantum Approximate Optimization Algorithm with Guaranteed Improvement.” <i>Physical Review A</i>. American Physical Society, 2023. <a href=\"https://doi.org/10.1103/physreva.107.062404\">https://doi.org/10.1103/physreva.107.062404</a>.","ista":"Sack S, Medina Ramos RA, Kueng R, Serbyn M. 2023. Recursive greedy initialization of the quantum approximate optimization algorithm with guaranteed improvement. Physical Review A. 107(6), 062404.","ieee":"S. Sack, R. A. Medina Ramos, R. Kueng, and M. Serbyn, “Recursive greedy initialization of the quantum approximate optimization algorithm with guaranteed improvement,” <i>Physical Review A</i>, vol. 107, no. 6. American Physical Society, 2023.","mla":"Sack, Stefan, et al. “Recursive Greedy Initialization of the Quantum Approximate Optimization Algorithm with Guaranteed Improvement.” <i>Physical Review A</i>, vol. 107, no. 6, 062404, American Physical Society, 2023, doi:<a href=\"https://doi.org/10.1103/physreva.107.062404\">10.1103/physreva.107.062404</a>."},"year":"2023","date_published":"2023-06-02T00:00:00Z","article_type":"original","abstract":[{"text":"The quantum approximate optimization algorithm (QAOA) is a variational quantum algorithm, where a quantum computer implements a variational ansatz consisting of p layers of alternating unitary operators and a classical computer is used to optimize the variational parameters. For a random initialization, the optimization typically leads to local minima with poor performance, motivating the search for initialization strategies of QAOA variational parameters. Although numerous heuristic initializations exist, an analytical understanding and performance guarantees for large p remain evasive.We introduce a greedy initialization of QAOA which guarantees improving performance with an increasing number of layers. Our main result is an analytic construction of 2p + 1 transition states—saddle points with a unique negative curvature direction—for QAOA with p + 1 layers that use the local minimum of QAOA with p layers. Transition states connect to new local minima, which are guaranteed to lower the energy compared to the minimum found for p layers. We use the GREEDY procedure to navigate the exponentially increasing with p number of local minima resulting from the recursive application of our analytic construction. The performance of the GREEDY procedure matches available initialization strategies while providing a guarantee for the minimal energy to decrease with an increasing number of layers p. ","lang":"eng"}],"project":[{"name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control","call_identifier":"H2020","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","grant_number":"850899"}],"external_id":{"isi":["001016927100012"],"arxiv":["2209.01159"]},"quality_controlled":"1","ec_funded":1,"day":"02","volume":107,"oa_version":"Published Version","type":"journal_article","author":[{"last_name":"Sack","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","full_name":"Sack, Stefan","first_name":"Stefan","orcid":"0000-0001-5400-8508"},{"first_name":"Raimel A","orcid":"0000-0002-5383-2869","last_name":"Medina Ramos","full_name":"Medina Ramos, Raimel A","id":"CE680B90-D85A-11E9-B684-C920E6697425"},{"last_name":"Kueng","full_name":"Kueng, Richard","first_name":"Richard"},{"orcid":"0000-0002-2399-5827","first_name":"Maksym","full_name":"Serbyn, Maksym","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","last_name":"Serbyn"}],"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","acknowledgement":"We thank V. Verteletskyi for a joint collaboration on numerical studies of the QAOA during his internship at ISTA that inspired analytic results on TS reported in this work. We acknowledge A. A. Mele and M. Brooks for discussions and D. Egger, P. Love, and D. Wierichs for valuable feedback on the manuscript. S.H.S., R.A.M., and M.S. acknowledge support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 850899). R.K. is supported by the SFB BeyondC (Grant No. F7107-N38) and the project QuantumReady (FFG 896217). ","issue":"6","corr_author":"1","file_date_updated":"2023-06-13T07:28:36Z","arxiv":1,"_id":"13125","related_material":{"record":[{"status":"public","id":"17208","relation":"dissertation_contains"},{"relation":"dissertation_contains","id":"14622","status":"public"}]},"oa":1,"intvolume":"       107","ddc":["530"],"file":[{"checksum":"0d71423888eeccaa60d8f41197f26306","date_created":"2023-06-13T07:28:36Z","file_size":2524611,"relation":"main_file","success":1,"access_level":"open_access","content_type":"application/pdf","date_updated":"2023-06-13T07:28:36Z","file_name":"2023_PhysRevA_Sack.pdf","file_id":"13131","creator":"dernst"}],"language":[{"iso":"eng"}],"publication":"Physical Review A","has_accepted_license":"1","scopus_import":"1","status":"public","date_created":"2023-06-07T06:57:32Z"},{"publication":"Physical Review Research","language":[{"iso":"eng"}],"has_accepted_license":"1","date_created":"2023-01-08T23:00:53Z","status":"public","scopus_import":"1","intvolume":"         4","ddc":["530"],"file":[{"creator":"dernst","file_id":"12328","file_name":"2022_PhysicalReviewResearch_Stocker.pdf","date_updated":"2023-01-20T12:03:31Z","content_type":"application/pdf","success":1,"access_level":"open_access","relation":"main_file","file_size":2941167,"date_created":"2023-01-20T12:03:31Z","checksum":"556820cf6e4af77c8476e5b8f4114d1a"}],"_id":"12111","oa":1,"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","acknowledgement":"We thank G. Blatter, T. Ihn, K. Ensslin, M. Goldstein, C. Carisch, and J. del Pino for illuminating discussions and acknowledge financial support from the Swiss National Science Foundation (SNSF) through Project No. 190078, and from the Deutsche Forschungsgemeinschaft (DFG) - Project No. 449653034. Our numerical implementations are based on the ITensors JULIA library [64].","author":[{"full_name":"Stocker, Lidia","last_name":"Stocker","first_name":"Lidia"},{"last_name":"Sack","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","full_name":"Sack, Stefan","first_name":"Stefan"},{"first_name":"Michael S.","full_name":"Ferguson, Michael S.","last_name":"Ferguson"},{"first_name":"Oded","full_name":"Zilberberg, Oded","last_name":"Zilberberg"}],"type":"journal_article","issue":"4","file_date_updated":"2023-01-20T12:03:31Z","quality_controlled":"1","volume":4,"oa_version":"Published Version","day":"01","article_type":"original","abstract":[{"lang":"eng","text":"Quantum impurities exhibit fascinating many-body phenomena when the small interacting impurity changes the physics of a large noninteracting environment. The characterisation of such strongly correlated nonperturbative effects is particularly challenging due to the infinite size of the environment, and the inability of local correlators to capture the buildup of long-ranged entanglement in the system. Here, we harness an entanglement-based observable—the purity of the impurity—as a witness for the formation of strong correlations. We showcase the utility of our scheme by exactly solving the open Kondo box model in the small box limit, and thus describe all-electronic dot-cavity devices. Specifically, we conclusively characterize the metal-to-insulator phase transition in the system and identify how the (conducting) dot-lead Kondo singlet is quenched by an (insulating) intraimpurity singlet formation. Furthermore, we propose an experimentally feasible tomography protocol for the measurement of the purity, which motivates the observation of impurity physics through their entanglement build up."}],"publisher":"American Physical Society","publication_identifier":{"issn":["2643-1564"]},"article_processing_charge":"No","doi":"10.1103/PhysRevResearch.4.043177","publication_status":"published","year":"2022","date_published":"2022-12-01T00:00:00Z","citation":{"ieee":"L. Stocker, S. Sack, M. S. Ferguson, and O. Zilberberg, “Entanglement-based observables for quantum impurities,” <i>Physical Review Research</i>, vol. 4, no. 4. American Physical Society, 2022.","mla":"Stocker, Lidia, et al. “Entanglement-Based Observables for Quantum Impurities.” <i>Physical Review Research</i>, vol. 4, no. 4, 043177, American Physical Society, 2022, doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.4.043177\">10.1103/PhysRevResearch.4.043177</a>.","ista":"Stocker L, Sack S, Ferguson MS, Zilberberg O. 2022. Entanglement-based observables for quantum impurities. Physical Review Research. 4(4), 043177.","ama":"Stocker L, Sack S, Ferguson MS, Zilberberg O. Entanglement-based observables for quantum impurities. <i>Physical Review Research</i>. 2022;4(4). doi:<a href=\"https://doi.org/10.1103/PhysRevResearch.4.043177\">10.1103/PhysRevResearch.4.043177</a>","chicago":"Stocker, Lidia, Stefan Sack, Michael S. Ferguson, and Oded Zilberberg. “Entanglement-Based Observables for Quantum Impurities.” <i>Physical Review Research</i>. American Physical Society, 2022. <a href=\"https://doi.org/10.1103/PhysRevResearch.4.043177\">https://doi.org/10.1103/PhysRevResearch.4.043177</a>.","short":"L. Stocker, S. Sack, M.S. Ferguson, O. Zilberberg, Physical Review Research 4 (2022).","apa":"Stocker, L., Sack, S., Ferguson, M. S., &#38; Zilberberg, O. (2022). Entanglement-based observables for quantum impurities. <i>Physical Review Research</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevResearch.4.043177\">https://doi.org/10.1103/PhysRevResearch.4.043177</a>"},"article_number":"043177","title":"Entanglement-based observables for quantum impurities","date_updated":"2023-02-13T09:08:28Z","department":[{"_id":"MaSe"}],"month":"12","tmp":{"legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"}}]