---
OA_place: publisher
OA_type: hybrid
_id: '18923'
abstract:
- lang: eng
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.”'
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)."
article_processing_charge: Yes (in subscription journal)
article_type: original
author:
- first_name: Jonathan
full_name: Wurtz, Jonathan
last_name: Wurtz
- first_name: Stefan
full_name: Sack, Stefan
id: dd622248-f6e0-11ea-865d-ce382a1c81a5
last_name: Sack
orcid: 0000-0001-5400-8508
- first_name: Sheng-Tao
full_name: Wang, Sheng-Tao
last_name: Wang
citation:
ama: Wurtz J, Sack S, Wang S-T. Solving nonnative combinatorial optimization problems
using hybrid quantum–classical algorithms. IEEE Transactions on Quantum Engineering.
2024;5:1-14. doi:10.1109/tqe.2024.3443660
apa: Wurtz, J., Sack, S., & Wang, S.-T. (2024). Solving nonnative combinatorial
optimization problems using hybrid quantum–classical algorithms. IEEE Transactions
on Quantum Engineering. Institute of Electrical and Electronics Engineers
. https://doi.org/10.1109/tqe.2024.3443660
chicago: Wurtz, Jonathan, Stefan Sack, and Sheng-Tao Wang. “Solving Nonnative Combinatorial
Optimization Problems Using Hybrid Quantum–Classical Algorithms.” IEEE Transactions
on Quantum Engineering. Institute of Electrical and Electronics Engineers
, 2024. https://doi.org/10.1109/tqe.2024.3443660.
ieee: J. Wurtz, S. Sack, and S.-T. Wang, “Solving nonnative combinatorial optimization
problems using hybrid quantum–classical algorithms,” IEEE Transactions on Quantum
Engineering, vol. 5. Institute of Electrical and Electronics Engineers , pp.
1–14, 2024.
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.
mla: Wurtz, Jonathan, et al. “Solving Nonnative Combinatorial Optimization Problems
Using Hybrid Quantum–Classical Algorithms.” IEEE Transactions on Quantum Engineering,
vol. 5, Institute of Electrical and Electronics Engineers , 2024, pp. 1–14, doi:10.1109/tqe.2024.3443660.
short: J. Wurtz, S. Sack, S.-T. Wang, IEEE Transactions on Quantum Engineering 5
(2024) 1–14.
date_created: 2025-01-27T15:00:44Z
date_published: 2024-08-14T00:00:00Z
date_updated: 2025-01-27T15:06:15Z
day: '14'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1109/tqe.2024.3443660
file:
- access_level: open_access
checksum: 19b84e35cba05bde72bfe7e0b54c3e6c
content_type: application/pdf
creator: dernst
date_created: 2025-01-27T15:03:09Z
date_updated: 2025-01-27T15:03:09Z
file_id: '18924'
file_name: 2024_IEEEQuantumComputing_Wurtz.pdf
file_size: 1753095
relation: main_file
success: 1
file_date_updated: 2025-01-27T15:03:09Z
has_accepted_license: '1'
intvolume: ' 5'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
page: 1-14
publication: IEEE Transactions on Quantum Engineering
publication_identifier:
issn:
- 2689-1808
publication_status: published
publisher: 'Institute of Electrical and Electronics Engineers '
quality_controlled: '1'
scopus_import: '1'
status: public
title: Solving nonnative combinatorial optimization problems using hybrid quantum–classical
algorithms
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 5
year: '2024'
...
---
_id: '15002'
abstract:
- lang: eng
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."
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."
article_number: '050401'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Elena
full_name: Petrova, Elena
id: 0ac84990-897b-11ed-a09c-f5abb56a4ede
last_name: Petrova
- first_name: Egor S.
full_name: Tiunov, Egor S.
last_name: Tiunov
- first_name: Mari Carmen
full_name: Bañuls, Mari Carmen
last_name: Bañuls
- first_name: Aleksey K.
full_name: Fedorov, Aleksey K.
last_name: Fedorov
citation:
ama: Petrova E, Tiunov ES, Bañuls MC, Fedorov AK. Fractal states of the Schwinger
model. Physical Review Letters. 2024;132(5). doi:10.1103/PhysRevLett.132.050401
apa: Petrova, E., Tiunov, E. S., Bañuls, M. C., & Fedorov, A. K. (2024). Fractal
states of the Schwinger model. Physical Review Letters. American Physical
Society. https://doi.org/10.1103/PhysRevLett.132.050401
chicago: Petrova, Elena, Egor S. Tiunov, Mari Carmen Bañuls, and Aleksey K. Fedorov.
“Fractal States of the Schwinger Model.” Physical Review Letters. American
Physical Society, 2024. https://doi.org/10.1103/PhysRevLett.132.050401.
ieee: E. Petrova, E. S. Tiunov, M. C. Bañuls, and A. K. Fedorov, “Fractal states
of the Schwinger model,” Physical Review Letters, vol. 132, no. 5. American
Physical Society, 2024.
ista: Petrova E, Tiunov ES, Bañuls MC, Fedorov AK. 2024. Fractal states of the Schwinger
model. Physical Review Letters. 132(5), 050401.
mla: Petrova, Elena, et al. “Fractal States of the Schwinger Model.” Physical
Review Letters, vol. 132, no. 5, 050401, American Physical Society, 2024,
doi:10.1103/PhysRevLett.132.050401.
short: E. Petrova, E.S. Tiunov, M.C. Bañuls, A.K. Fedorov, Physical Review Letters
132 (2024).
date_created: 2024-02-18T23:01:00Z
date_published: 2024-01-30T00:00:00Z
date_updated: 2025-09-04T12:02:33Z
day: '30'
department:
- _id: MaSe
doi: 10.1103/PhysRevLett.132.050401
external_id:
arxiv:
- '2201.10220'
isi:
- '001179276700003'
pmid:
- '38364163'
intvolume: ' 132'
isi: 1
issue: '5'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2201.10220
month: '01'
oa: 1
oa_version: Preprint
pmid: 1
publication: Physical Review Letters
publication_identifier:
eissn:
- 1079-7114
issn:
- 0031-9007
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Fractal states of the Schwinger model
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 132
year: '2024'
...
---
DOAJ_listed: '1'
_id: '15122'
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.
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.
article_number: '013223'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Stefan
full_name: Sack, Stefan
id: dd622248-f6e0-11ea-865d-ce382a1c81a5
last_name: Sack
orcid: 0000-0001-5400-8508
- first_name: Daniel J.
full_name: Egger, Daniel J.
last_name: Egger
citation:
ama: Sack S, Egger DJ. Large-scale quantum approximate optimization on nonplanar
graphs with machine learning noise mitigation. Physical Review Research.
2024;6(1). doi:10.1103/PhysRevResearch.6.013223
apa: Sack, S., & Egger, D. J. (2024). Large-scale quantum approximate optimization
on nonplanar graphs with machine learning noise mitigation. Physical Review
Research. American Physical Society. https://doi.org/10.1103/PhysRevResearch.6.013223
chicago: Sack, Stefan, and Daniel J. Egger. “Large-Scale Quantum Approximate Optimization
on Nonplanar Graphs with Machine Learning Noise Mitigation.” Physical Review
Research. American Physical Society, 2024. https://doi.org/10.1103/PhysRevResearch.6.013223.
ieee: S. Sack and D. J. Egger, “Large-scale quantum approximate optimization on
nonplanar graphs with machine learning noise mitigation,” Physical Review Research,
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.
mla: Sack, Stefan, and Daniel J. Egger. “Large-Scale Quantum Approximate Optimization
on Nonplanar Graphs with Machine Learning Noise Mitigation.” Physical Review
Research, vol. 6, no. 1, 013223, American Physical Society, 2024, doi:10.1103/PhysRevResearch.6.013223.
short: S. Sack, D.J. Egger, Physical Review Research 6 (2024).
corr_author: '1'
date_created: 2024-03-17T23:00:59Z
date_published: 2024-03-01T00:00:00Z
date_updated: 2025-05-14T09:32:15Z
day: '01'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/PhysRevResearch.6.013223
external_id:
arxiv:
- '2307.14427'
file:
- access_level: open_access
checksum: 274c9f1b15b3547a10a03f39e4ccc582
content_type: application/pdf
creator: dernst
date_created: 2024-03-19T07:16:38Z
date_updated: 2024-03-19T07:16:38Z
file_id: '15123'
file_name: 2024_PhysicalReviewResearch_Sack.pdf
file_size: 2777593
relation: main_file
success: 1
file_date_updated: 2024-03-19T07:16:38Z
has_accepted_license: '1'
intvolume: ' 6'
issue: '1'
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
project:
- _id: bd660c93-d553-11ed-ba76-fb0fb6f49c0d
name: IMB PhD Nomination Fellowship - Stefan Sack
publication: Physical Review Research
publication_identifier:
eissn:
- 2643-1564
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Large-scale quantum approximate optimization on nonplanar graphs with machine
learning noise mitigation
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 6
year: '2024'
...
---
_id: '15367'
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.
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."
article_number: '115'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Serafim
full_name: Babkin, Serafim
id: 41e64307-6672-11ee-b9ad-cc7a0075a479
last_name: Babkin
orcid: 0009-0003-7382-8036
- first_name: Andrew P
full_name: Higginbotham, Andrew P
id: 4AD6785A-F248-11E8-B48F-1D18A9856A87
last_name: Higginbotham
orcid: 0000-0003-2607-2363
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Babkin S, Higginbotham AP, Serbyn M. Proximity-induced gapless superconductivity
in two-dimensional Rashba semiconductor in magnetic field. SciPost Physics.
2024;16(5). doi:10.21468/scipostphys.16.5.115
apa: Babkin, S., Higginbotham, A. P., & Serbyn, M. (2024). Proximity-induced
gapless superconductivity in two-dimensional Rashba semiconductor in magnetic
field. SciPost Physics. SciPost Foundation. https://doi.org/10.21468/scipostphys.16.5.115
chicago: Babkin, Serafim, Andrew P Higginbotham, and Maksym Serbyn. “Proximity-Induced
Gapless Superconductivity in Two-Dimensional Rashba Semiconductor in Magnetic
Field.” SciPost Physics. SciPost Foundation, 2024. https://doi.org/10.21468/scipostphys.16.5.115.
ieee: S. Babkin, A. P. Higginbotham, and M. Serbyn, “Proximity-induced gapless superconductivity
in two-dimensional Rashba semiconductor in magnetic field,” SciPost Physics,
vol. 16, no. 5. SciPost Foundation, 2024.
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.
mla: Babkin, Serafim, et al. “Proximity-Induced Gapless Superconductivity in Two-Dimensional
Rashba Semiconductor in Magnetic Field.” SciPost Physics, vol. 16, no.
5, 115, SciPost Foundation, 2024, doi:10.21468/scipostphys.16.5.115.
short: S. Babkin, A.P. Higginbotham, M. Serbyn, SciPost Physics 16 (2024).
corr_author: '1'
date_created: 2024-05-06T09:02:18Z
date_published: 2024-05-01T00:00:00Z
date_updated: 2025-09-04T13:53:20Z
day: '01'
ddc:
- '530'
department:
- _id: MaSe
- _id: AnHi
doi: 10.21468/scipostphys.16.5.115
external_id:
arxiv:
- '2311.09347'
isi:
- '001215855200002'
file:
- access_level: open_access
checksum: f999204856417dcf5a736ac8df432b96
content_type: application/pdf
creator: dernst
date_created: 2024-05-07T12:58:47Z
date_updated: 2024-05-07T12:58:47Z
file_id: '15369'
file_name: 2024_SciPostPhys_Babkin.pdf
file_size: 2733685
relation: main_file
success: 1
file_date_updated: 2024-05-07T12:58:47Z
has_accepted_license: '1'
intvolume: ' 16'
isi: 1
issue: '5'
language:
- iso: eng
month: '05'
oa: 1
oa_version: Published Version
project:
- _id: eb9b30ac-77a9-11ec-83b8-871f581d53d2
name: Protected states of quantum matter
- _id: 34a7f947-11ca-11ed-8bc3-c5dc2bbaae25
grant_number: F8609
name: 'Center for Correlated Quantum Materials and Solid State Quantum Systems: Probing
topology in circuits and quantum materials'
publication: SciPost Physics
publication_identifier:
issn:
- 2542-4653
publication_status: published
publisher: SciPost Foundation
quality_controlled: '1'
scopus_import: '1'
status: public
title: Proximity-induced gapless superconductivity in two-dimensional Rashba semiconductor
in magnetic field
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 16
year: '2024'
...
---
_id: '17471'
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.
article_processing_charge: No
author:
- first_name: Jean-Yves Marc
full_name: Desaules, Jean-Yves Marc
id: 6c292945-a610-11ed-9eec-c3be1ad62a80
last_name: Desaules
orcid: 0000-0002-3749-6375
citation:
ama: Desaules J-YM. Data for “Enhanced many-body quantum scars from the non-Hermitian
Fock skin effect.” 2024. doi:10.15479/AT:ISTA:17471
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.
https://doi.org/10.15479/AT:ISTA:17471
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. https://doi.org/10.15479/AT:ISTA:17471.
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.
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, 10.15479/AT:ISTA:17471.
mla: 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, doi:10.15479/AT:ISTA:17471.
short: J.-Y.M. Desaules, (2024).
contributor:
- contributor_type: researcher
first_name: Ruizhe
last_name: Shen
- contributor_type: researcher
first_name: Fang
last_name: Qin
- contributor_type: researcher
first_name: Jean-Yves Marc
id: 6c292945-a610-11ed-9eec-c3be1ad62a80
last_name: Desaules
orcid: 0000-0002-3749-6375
- contributor_type: researcher
first_name: Zlatko
last_name: Papić
- contributor_type: researcher
first_name: Ching Hua
last_name: Lee
date_created: 2024-08-30T12:59:43Z
date_published: 2024-08-30T00:00:00Z
date_updated: 2025-09-08T14:54:55Z
day: '30'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.15479/AT:ISTA:17471
ec_funded: 1
file:
- access_level: open_access
checksum: 2bd49ce5a63f1951c1ed3d89cce4fe27
content_type: application/zip
creator: jdesaule
date_created: 2024-08-30T12:55:37Z
date_updated: 2024-08-30T12:55:37Z
file_id: '17472'
file_name: FiguresData.zip
file_size: 322400
relation: main_file
success: 1
- access_level: open_access
checksum: c2ba113a241e98c394cc3ca21f3fa126
content_type: text/plain
creator: jdesaule
date_created: 2024-08-30T13:19:57Z
date_updated: 2024-08-30T13:19:57Z
file_id: '17473'
file_name: readme.txt
file_size: 1368
relation: main_file
success: 1
file_date_updated: 2024-08-30T13:19:57Z
has_accepted_license: '1'
keyword:
- quantum many-body scars
- non-equilibrium physics
- non-Hermitian physics
license: https://creativecommons.org/licenses/by-nc/4.0/
month: '08'
oa: 1
oa_version: None
project:
- _id: fc2ed2f7-9c52-11eb-aca3-c01059dda49c
call_identifier: H2020
grant_number: '101034413'
name: 'IST-BRIDGE: International postdoctoral program'
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '18627'
relation: used_in_publication
status: public
status: public
title: Data for "Enhanced many-body quantum scars from the non-Hermitian Fock skin
effect"
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)
type: research_data
user_id: 68b8ca59-c5b3-11ee-8790-cd641c68093d
year: '2024'
...
---
APC_amount: 4863,6 EUR
DOAJ_listed: '1'
OA_place: publisher
OA_type: gold
_id: '17493'
abstract:
- lang: eng
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.
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).
article_number: '031035'
article_processing_charge: Yes
article_type: original
arxiv: 1
author:
- first_name: Benoît
full_name: Vermersch, Benoît
last_name: Vermersch
- first_name: Marko
full_name: Ljubotina, Marko
id: F75EE9BE-5C90-11EA-905D-16643DDC885E
last_name: Ljubotina
orcid: 0000-0003-0038-7068
- first_name: J. Ignacio
full_name: Cirac, J. Ignacio
last_name: Cirac
- first_name: Peter
full_name: Zoller, Peter
last_name: Zoller
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
- first_name: Lorenzo
full_name: Piroli, Lorenzo
last_name: Piroli
citation:
ama: Vermersch B, Ljubotina M, Cirac JI, Zoller P, Serbyn M, Piroli L. Many-body
entropies and entanglement from polynomially many local measurements. Physical
Review X. 2024;14(3). doi:10.1103/physrevx.14.031035
apa: Vermersch, B., Ljubotina, M., Cirac, J. I., Zoller, P., Serbyn, M., & Piroli,
L. (2024). Many-body entropies and entanglement from polynomially many local measurements.
Physical Review X. American Physical Society. https://doi.org/10.1103/physrevx.14.031035
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.” Physical Review X. American Physical Society,
2024. https://doi.org/10.1103/physrevx.14.031035.
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,”
Physical Review X, 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.
mla: Vermersch, Benoît, et al. “Many-Body Entropies and Entanglement from Polynomially
Many Local Measurements.” Physical Review X, vol. 14, no. 3, 031035, American
Physical Society, 2024, doi:10.1103/physrevx.14.031035.
short: B. Vermersch, M. Ljubotina, J.I. Cirac, P. Zoller, M. Serbyn, L. Piroli,
Physical Review X 14 (2024).
date_created: 2024-09-04T18:57:11Z
date_published: 2024-08-26T00:00:00Z
date_updated: 2025-09-08T09:04:14Z
day: '26'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/physrevx.14.031035
ec_funded: 1
external_id:
arxiv:
- '2311.08108'
isi:
- '001299667100002'
file:
- access_level: open_access
checksum: 1b114acc89025120727200681e4e9074
content_type: application/pdf
creator: cchlebak
date_created: 2024-09-05T09:39:00Z
date_updated: 2024-09-05T09:39:00Z
file_id: '17532'
file_name: 2024_PhysRevX_Vermersch.pdf
file_size: 1408836
relation: main_file
success: 1
file_date_updated: 2024-09-05T09:39:00Z
has_accepted_license: '1'
intvolume: ' 14'
isi: 1
issue: '3'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review X
publication_identifier:
issn:
- 2160-3308
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Many-body entropies and entanglement from polynomially many local measurements
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 14
year: '2024'
...
---
OA_place: publisher
_id: '17208'
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."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Raimel A
full_name: Medina Ramos, Raimel A
id: CE680B90-D85A-11E9-B684-C920E6697425
last_name: Medina Ramos
orcid: 0000-0002-5383-2869
citation:
ama: Medina Ramos RA. Exploring the optimization landscape of variational quantum
algorithms. 2024. doi:10.15479/at:ista:17208
apa: Medina Ramos, R. A. (2024). Exploring the optimization landscape of variational
quantum algorithms. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:17208
chicago: Medina Ramos, Raimel A. “Exploring the Optimization Landscape of Variational
Quantum Algorithms.” Institute of Science and Technology Austria, 2024. https://doi.org/10.15479/at:ista:17208.
ieee: R. A. Medina Ramos, “Exploring the optimization landscape of variational quantum
algorithms,” Institute of Science and Technology Austria, 2024.
ista: Medina Ramos RA. 2024. Exploring the optimization landscape of variational
quantum algorithms. Institute of Science and Technology Austria.
mla: Medina Ramos, Raimel A. Exploring the Optimization Landscape of Variational
Quantum Algorithms. Institute of Science and Technology Austria, 2024, doi:10.15479/at:ista:17208.
short: R.A. Medina Ramos, Exploring the Optimization Landscape of Variational Quantum
Algorithms, Institute of Science and Technology Austria, 2024.
corr_author: '1'
date_created: 2024-07-09T09:14:24Z
date_published: 2024-07-09T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '09'
ddc:
- '539'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaSe
doi: 10.15479/at:ista:17208
ec_funded: 1
file:
- access_level: closed
checksum: 6f45273d04f4418bc2adc018baed0525
content_type: application/zip
creator: rmedinar
date_created: 2024-07-09T09:21:44Z
date_updated: 2024-07-10T11:34:09Z
file_id: '17212'
file_name: Raimel_Thesis-Final.zip
file_size: '14218691'
relation: source_file
- access_level: open_access
checksum: 6724a95bec772dbabc0111b9f08a805e
content_type: application/pdf
creator: rmedinar
date_created: 2024-07-17T09:23:24Z
date_updated: 2024-07-17T09:23:24Z
file_id: '17275'
file_name: Raimel_Thesis-20_pdfa.pdf
file_size: 11253627
relation: main_file
success: 1
file_date_updated: 2024-07-17T09:23:24Z
has_accepted_license: '1'
keyword:
- Quantum computing
- Variational Quantum Algorithms
- Optimization
language:
- iso: eng
month: '07'
oa: 1
oa_version: Published Version
page: '133'
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '10545'
relation: part_of_dissertation
status: public
- id: '10067'
relation: part_of_dissertation
status: public
- id: '17222'
relation: part_of_dissertation
status: public
- id: '13125'
relation: part_of_dissertation
status: public
- id: '11471'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
title: Exploring the optimization landscape of variational quantum algorithms
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2024'
...
---
OA_place: repository
_id: '17222'
abstract:
- lang: eng
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."
article_number: '2405.10125'
article_processing_charge: No
arxiv: 1
author:
- first_name: Raimel A
full_name: Medina Ramos, Raimel A
id: CE680B90-D85A-11E9-B684-C920E6697425
last_name: Medina Ramos
orcid: 0000-0002-5383-2869
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Medina Ramos RA, Serbyn M. A recursive lower bound on the energy improvement
of the quantum approximate optimization algorithm. arXiv. doi:10.48550/arXiv.2405.10125
apa: Medina Ramos, R. A., & Serbyn, M. (n.d.). A recursive lower bound on the
energy improvement of the quantum approximate optimization algorithm. arXiv.
https://doi.org/10.48550/arXiv.2405.10125
chicago: Medina Ramos, Raimel A, and Maksym Serbyn. “A Recursive Lower Bound on
the Energy Improvement of the Quantum Approximate Optimization Algorithm.” ArXiv,
n.d. https://doi.org/10.48550/arXiv.2405.10125.
ieee: R. A. Medina Ramos and M. Serbyn, “A recursive lower bound on the energy improvement
of the quantum approximate optimization algorithm,” arXiv. .
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.” ArXiv,
2405.10125, doi:10.48550/arXiv.2405.10125.
short: R.A. Medina Ramos, M. Serbyn, ArXiv (n.d.).
corr_author: '1'
date_created: 2024-07-10T13:12:09Z
date_published: 2024-05-16T00:00:00Z
date_updated: 2026-04-07T12:43:22Z
day: '16'
department:
- _id: MaSe
doi: 10.48550/arXiv.2405.10125
external_id:
arxiv:
- '2405.10125'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2405.10125
month: '05'
oa: 1
oa_version: Preprint
publication: arXiv
publication_status: draft
related_material:
record:
- id: '17208'
relation: dissertation_contains
status: public
status: public
title: A recursive lower bound on the energy improvement of the quantum approximate
optimization algorithm
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: preprint
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
year: '2024'
...
---
_id: '13963'
abstract:
- lang: eng
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.
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]."
article_number: '054201'
article_processing_charge: Yes (in subscription journal)
article_type: original
arxiv: 1
author:
- first_name: Pietro
full_name: Brighi, Pietro
id: 4115AF5C-F248-11E8-B48F-1D18A9856A87
last_name: Brighi
orcid: 0000-0002-7969-2729
- first_name: Marko
full_name: Ljubotina, Marko
id: F75EE9BE-5C90-11EA-905D-16643DDC885E
last_name: Ljubotina
orcid: 0000-0003-0038-7068
- first_name: Dmitry A.
full_name: Abanin, Dmitry A.
last_name: Abanin
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Brighi P, Ljubotina M, Abanin DA, Serbyn M. Many-body localization proximity
effect in a two-species bosonic Hubbard model. Physical Review B. 2023;108(5).
doi:10.1103/physrevb.108.054201
apa: Brighi, P., Ljubotina, M., Abanin, D. A., & Serbyn, M. (2023). Many-body
localization proximity effect in a two-species bosonic Hubbard model. Physical
Review B. American Physical Society. https://doi.org/10.1103/physrevb.108.054201
chicago: Brighi, Pietro, Marko Ljubotina, Dmitry A. Abanin, and Maksym Serbyn. “Many-Body
Localization Proximity Effect in a Two-Species Bosonic Hubbard Model.” Physical
Review B. American Physical Society, 2023. https://doi.org/10.1103/physrevb.108.054201.
ieee: P. Brighi, M. Ljubotina, D. A. Abanin, and M. Serbyn, “Many-body localization
proximity effect in a two-species bosonic Hubbard model,” Physical Review B,
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.
mla: Brighi, Pietro, et al. “Many-Body Localization Proximity Effect in a Two-Species
Bosonic Hubbard Model.” Physical Review B, vol. 108, no. 5, 054201, American
Physical Society, 2023, doi:10.1103/physrevb.108.054201.
short: P. Brighi, M. Ljubotina, D.A. Abanin, M. Serbyn, Physical Review B 108 (2023).
corr_author: '1'
date_created: 2023-08-05T18:25:22Z
date_published: 2023-08-01T00:00:00Z
date_updated: 2025-04-14T07:52:06Z
day: '01'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/physrevb.108.054201
ec_funded: 1
external_id:
arxiv:
- '2303.16876'
file:
- access_level: open_access
checksum: f763000339b5fd543c14377109920690
content_type: application/pdf
creator: dernst
date_created: 2023-08-07T09:48:08Z
date_updated: 2023-08-07T09:48:08Z
file_id: '13981'
file_name: 2023_PhysRevB_Brighi.pdf
file_size: 3051398
relation: main_file
success: 1
file_date_updated: 2023-08-07T09:48:08Z
has_accepted_license: '1'
intvolume: ' 108'
issue: '5'
language:
- iso: eng
month: '08'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Many-body localization proximity effect in a two-species bosonic Hubbard model
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 108
year: '2023'
...
---
_id: '14320'
abstract:
- lang: eng
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.
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.
article_number: '125411'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Paul M
full_name: Henderson, Paul M
id: 13C09E74-18D9-11E9-8878-32CFE5697425
last_name: Henderson
orcid: 0000-0002-5198-7445
- first_name: Areg
full_name: Ghazaryan, Areg
id: 4AF46FD6-F248-11E8-B48F-1D18A9856A87
last_name: Ghazaryan
orcid: 0000-0001-9666-3543
- first_name: Alexander A.
full_name: Zibrov, Alexander A.
last_name: Zibrov
- first_name: Andrea F.
full_name: Young, Andrea F.
last_name: Young
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
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. Physical Review B. 2023;108(12). doi:10.1103/physrevb.108.125411'
apa: 'Henderson, P. M., Ghazaryan, A., Zibrov, A. A., Young, A. F., & Serbyn,
M. (2023). Deep learning extraction of band structure parameters from density
of states: A case study on trilayer graphene. Physical Review B. American
Physical Society. https://doi.org/10.1103/physrevb.108.125411'
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.” Physical Review B.
American Physical Society, 2023. https://doi.org/10.1103/physrevb.108.125411.'
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,” Physical Review B, vol. 108, no. 12.
American Physical Society, 2023.'
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.” Physical Review
B, vol. 108, no. 12, 125411, American Physical Society, 2023, doi:10.1103/physrevb.108.125411.'
short: P.M. Henderson, A. Ghazaryan, A.A. Zibrov, A.F. Young, M. Serbyn, Physical
Review B 108 (2023).
date_created: 2023-09-12T07:12:12Z
date_published: 2023-09-15T00:00:00Z
date_updated: 2023-09-20T09:38:24Z
day: '15'
department:
- _id: MaSe
- _id: ChLa
- _id: MiLe
doi: 10.1103/physrevb.108.125411
external_id:
arxiv:
- '2210.06310'
intvolume: ' 108'
issue: '12'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2210.06310
month: '09'
oa: 1
oa_version: Preprint
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: 'Deep learning extraction of band structure parameters from density of states:
A case study on trilayer graphene'
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 108
year: '2023'
...
---
_id: '14334'
abstract:
- lang: eng
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.
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)."
article_number: '093'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Pietro
full_name: Brighi, Pietro
id: 4115AF5C-F248-11E8-B48F-1D18A9856A87
last_name: Brighi
orcid: 0000-0002-7969-2729
- first_name: Marko
full_name: Ljubotina, Marko
id: F75EE9BE-5C90-11EA-905D-16643DDC885E
last_name: Ljubotina
orcid: 0000-0003-0038-7068
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Brighi P, Ljubotina M, Serbyn M. Hilbert space fragmentation and slow dynamics
in particle-conserving quantum East models. SciPost Physics. 2023;15(3).
doi:10.21468/scipostphys.15.3.093
apa: Brighi, P., Ljubotina, M., & Serbyn, M. (2023). Hilbert space fragmentation
and slow dynamics in particle-conserving quantum East models. SciPost Physics.
SciPost Foundation. https://doi.org/10.21468/scipostphys.15.3.093
chicago: Brighi, Pietro, Marko Ljubotina, and Maksym Serbyn. “Hilbert Space Fragmentation
and Slow Dynamics in Particle-Conserving Quantum East Models.” SciPost Physics.
SciPost Foundation, 2023. https://doi.org/10.21468/scipostphys.15.3.093.
ieee: P. Brighi, M. Ljubotina, and M. Serbyn, “Hilbert space fragmentation and slow
dynamics in particle-conserving quantum East models,” SciPost Physics,
vol. 15, no. 3. SciPost Foundation, 2023.
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.
mla: Brighi, Pietro, et al. “Hilbert Space Fragmentation and Slow Dynamics in Particle-Conserving
Quantum East Models.” SciPost Physics, vol. 15, no. 3, 093, SciPost Foundation,
2023, doi:10.21468/scipostphys.15.3.093.
short: P. Brighi, M. Ljubotina, M. Serbyn, SciPost Physics 15 (2023).
corr_author: '1'
date_created: 2023-09-14T13:08:23Z
date_published: 2023-09-13T00:00:00Z
date_updated: 2025-04-14T07:52:05Z
day: '13'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.21468/scipostphys.15.3.093
ec_funded: 1
external_id:
arxiv:
- '2210.15607'
file:
- access_level: open_access
checksum: 4cef6a8021f6b6c47ab2f2f2b1387ac2
content_type: application/pdf
creator: dernst
date_created: 2023-09-20T10:46:10Z
date_updated: 2023-09-20T10:46:10Z
file_id: '14350'
file_name: 2023_SciPostPhysics_Brighi.pdf
file_size: 4866506
relation: main_file
success: 1
file_date_updated: 2023-09-20T10:46:10Z
has_accepted_license: '1'
intvolume: ' 15'
issue: '3'
keyword:
- General Physics and Astronomy
language:
- iso: eng
month: '09'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: SciPost Physics
publication_identifier:
issn:
- 2542-4653
publication_status: published
publisher: SciPost Foundation
quality_controlled: '1'
related_material:
record:
- id: '12750'
relation: earlier_version
status: public
scopus_import: '1'
status: public
title: Hilbert space fragmentation and slow dynamics in particle-conserving quantum
East models
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 15
year: '2023'
...
---
_id: '14406'
abstract:
- lang: eng
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."
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)."
article_number: '104205'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Serafim
full_name: Babkin, Serafim
id: 41e64307-6672-11ee-b9ad-cc7a0075a479
last_name: Babkin
orcid: 0009-0003-7382-8036
- first_name: Jonas F.
full_name: Karcher, Jonas F.
last_name: Karcher
- first_name: Igor S.
full_name: Burmistrov, Igor S.
last_name: Burmistrov
- first_name: Alexander D.
full_name: Mirlin, Alexander D.
last_name: Mirlin
citation:
ama: Babkin S, Karcher JF, Burmistrov IS, Mirlin AD. Generalized surface multifractality
in two-dimensional disordered systems. Physical Review B. 2023;108(10).
doi:10.1103/PhysRevB.108.104205
apa: Babkin, S., Karcher, J. F., Burmistrov, I. S., & Mirlin, A. D. (2023).
Generalized surface multifractality in two-dimensional disordered systems. Physical
Review B. American Physical Society. https://doi.org/10.1103/PhysRevB.108.104205
chicago: Babkin, Serafim, Jonas F. Karcher, Igor S. Burmistrov, and Alexander D.
Mirlin. “Generalized Surface Multifractality in Two-Dimensional Disordered Systems.”
Physical Review B. American Physical Society, 2023. https://doi.org/10.1103/PhysRevB.108.104205.
ieee: S. Babkin, J. F. Karcher, I. S. Burmistrov, and A. D. Mirlin, “Generalized
surface multifractality in two-dimensional disordered systems,” Physical Review
B, vol. 108, no. 10. American Physical Society, 2023.
ista: Babkin S, Karcher JF, Burmistrov IS, Mirlin AD. 2023. Generalized surface
multifractality in two-dimensional disordered systems. Physical Review B. 108(10),
104205.
mla: Babkin, Serafim, et al. “Generalized Surface Multifractality in Two-Dimensional
Disordered Systems.” Physical Review B, vol. 108, no. 10, 104205, American
Physical Society, 2023, doi:10.1103/PhysRevB.108.104205.
short: S. Babkin, J.F. Karcher, I.S. Burmistrov, A.D. Mirlin, Physical Review B
108 (2023).
date_created: 2023-10-08T22:01:17Z
date_published: 2023-09-01T00:00:00Z
date_updated: 2025-09-09T13:03:44Z
day: '01'
department:
- _id: MaSe
doi: 10.1103/PhysRevB.108.104205
external_id:
arxiv:
- '2306.09455'
isi:
- '001186160100001'
intvolume: ' 108'
isi: 1
issue: '10'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2306.09455
month: '09'
oa: 1
oa_version: Preprint
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Generalized surface multifractality in two-dimensional disordered systems
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 108
year: '2023'
...
---
_id: '14690'
abstract:
- lang: eng
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.
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).
article_number: '205429'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Serafim
full_name: Babkin, Serafim
id: 41e64307-6672-11ee-b9ad-cc7a0075a479
last_name: Babkin
orcid: 0009-0003-7382-8036
- first_name: I
full_name: Burmistrov, I
last_name: Burmistrov
citation:
ama: Babkin S, Burmistrov I. Boundary multifractality in the spin quantum Hall symmetry
class with interaction. Physical Review B. 2023;108(20). doi:10.1103/PhysRevB.108.205429
apa: Babkin, S., & Burmistrov, I. (2023). Boundary multifractality in the spin
quantum Hall symmetry class with interaction. Physical Review B. American
Physical Society. https://doi.org/10.1103/PhysRevB.108.205429
chicago: Babkin, Serafim, and I Burmistrov. “Boundary Multifractality in the Spin
Quantum Hall Symmetry Class with Interaction.” Physical Review B. American
Physical Society, 2023. https://doi.org/10.1103/PhysRevB.108.205429.
ieee: S. Babkin and I. Burmistrov, “Boundary multifractality in the spin quantum
Hall symmetry class with interaction,” Physical Review B, vol. 108, no.
20. American Physical Society, 2023.
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.” Physical Review B, vol. 108, no.
20, 205429, American Physical Society, 2023, doi:10.1103/PhysRevB.108.205429.
short: S. Babkin, I. Burmistrov, Physical Review B 108 (2023).
corr_author: '1'
date_created: 2023-12-17T23:00:53Z
date_published: 2023-11-15T00:00:00Z
date_updated: 2025-09-09T14:00:09Z
day: '15'
department:
- _id: MaSe
doi: 10.1103/PhysRevB.108.205429
external_id:
arxiv:
- '2308.16852'
isi:
- '001141678200003'
intvolume: ' 108'
isi: 1
issue: '20'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: ' https://doi.org/10.48550/arXiv.2308.16852'
month: '11'
oa: 1
oa_version: Preprint
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Boundary multifractality in the spin quantum Hall symmetry class with interaction
type: journal_article
user_id: 317138e5-6ab7-11ef-aa6d-ffef3953e345
volume: 108
year: '2023'
...
---
_id: '12790'
abstract:
- lang: eng
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.
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.
article_number: '104502'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Areg
full_name: Ghazaryan, Areg
id: 4AF46FD6-F248-11E8-B48F-1D18A9856A87
last_name: Ghazaryan
orcid: 0000-0001-9666-3543
- first_name: Tobias
full_name: Holder, Tobias
last_name: Holder
- first_name: Erez
full_name: Berg, Erez
last_name: Berg
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Ghazaryan A, Holder T, Berg E, Serbyn M. Multilayer graphenes as a platform
for interaction-driven physics and topological superconductivity. Physical
Review B. 2023;107(10). doi:10.1103/PhysRevB.107.104502
apa: Ghazaryan, A., Holder, T., Berg, E., & Serbyn, M. (2023). Multilayer graphenes
as a platform for interaction-driven physics and topological superconductivity.
Physical Review B. American Physical Society. https://doi.org/10.1103/PhysRevB.107.104502
chicago: Ghazaryan, Areg, Tobias Holder, Erez Berg, and Maksym Serbyn. “Multilayer
Graphenes as a Platform for Interaction-Driven Physics and Topological Superconductivity.”
Physical Review B. American Physical Society, 2023. https://doi.org/10.1103/PhysRevB.107.104502.
ieee: A. Ghazaryan, T. Holder, E. Berg, and M. Serbyn, “Multilayer graphenes as
a platform for interaction-driven physics and topological superconductivity,”
Physical Review B, vol. 107, no. 10. American Physical Society, 2023.
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.” Physical Review B, vol. 107,
no. 10, 104502, American Physical Society, 2023, doi:10.1103/PhysRevB.107.104502.
short: A. Ghazaryan, T. Holder, E. Berg, M. Serbyn, Physical Review B 107 (2023).
date_created: 2023-04-02T22:01:10Z
date_published: 2023-03-01T00:00:00Z
date_updated: 2023-08-01T13:59:29Z
day: '01'
department:
- _id: MaSe
- _id: MiLe
doi: 10.1103/PhysRevB.107.104502
external_id:
arxiv:
- '2211.02492'
isi:
- '000945526400003'
intvolume: ' 107'
isi: 1
issue: '10'
language:
- iso: eng
main_file_link:
- open_access: '1'
url: https://doi.org/10.48550/arXiv.2211.02492
month: '03'
oa: 1
oa_version: Preprint
publication: Physical Review B
publication_identifier:
eissn:
- 2469-9969
issn:
- 2469-9950
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
link:
- description: News on the ISTA website
relation: press_release
url: https://ista.ac.at/en/news/reaching-superconductivity-layer-by-layer/
scopus_import: '1'
status: public
title: Multilayer graphenes as a platform for interaction-driven physics and topological
superconductivity
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 107
year: '2023'
...
---
_id: '12839'
abstract:
- lang: eng
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.
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]."
article_number: '011033'
article_processing_charge: No
article_type: original
author:
- first_name: Marko
full_name: Ljubotina, Marko
id: F75EE9BE-5C90-11EA-905D-16643DDC885E
last_name: Ljubotina
orcid: 0000-0003-0038-7068
- first_name: Jean Yves
full_name: Desaules, Jean Yves
last_name: Desaules
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
- first_name: Zlatko
full_name: Papić, Zlatko
last_name: Papić
citation:
ama: Ljubotina M, Desaules JY, Serbyn M, Papić Z. Superdiffusive energy transport
in kinetically constrained models. Physical Review X. 2023;13(1). doi:10.1103/PhysRevX.13.011033
apa: Ljubotina, M., Desaules, J. Y., Serbyn, M., & Papić, Z. (2023). Superdiffusive
energy transport in kinetically constrained models. Physical Review X.
American Physical Society. https://doi.org/10.1103/PhysRevX.13.011033
chicago: Ljubotina, Marko, Jean Yves Desaules, Maksym Serbyn, and Zlatko Papić.
“Superdiffusive Energy Transport in Kinetically Constrained Models.” Physical
Review X. American Physical Society, 2023. https://doi.org/10.1103/PhysRevX.13.011033.
ieee: M. Ljubotina, J. Y. Desaules, M. Serbyn, and Z. Papić, “Superdiffusive energy
transport in kinetically constrained models,” Physical Review X, vol. 13,
no. 1. American Physical Society, 2023.
ista: Ljubotina M, Desaules JY, Serbyn M, Papić Z. 2023. Superdiffusive energy transport
in kinetically constrained models. Physical Review X. 13(1), 011033.
mla: Ljubotina, Marko, et al. “Superdiffusive Energy Transport in Kinetically Constrained
Models.” Physical Review X, vol. 13, no. 1, 011033, American Physical Society,
2023, doi:10.1103/PhysRevX.13.011033.
short: M. Ljubotina, J.Y. Desaules, M. Serbyn, Z. Papić, Physical Review X 13 (2023).
corr_author: '1'
date_created: 2023-04-16T22:01:09Z
date_published: 2023-03-07T00:00:00Z
date_updated: 2025-04-14T07:52:07Z
day: '07'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/PhysRevX.13.011033
ec_funded: 1
external_id:
isi:
- '000957625700001'
file:
- access_level: open_access
checksum: ee060cea609af79bba7af74b1ce28078
content_type: application/pdf
creator: dernst
date_created: 2023-04-17T08:36:53Z
date_updated: 2023-04-17T08:36:53Z
file_id: '12845'
file_name: 2023_PhysReviewX_Ljubotina.pdf
file_size: 1958523
relation: main_file
success: 1
file_date_updated: 2023-04-17T08:36:53Z
has_accepted_license: '1'
intvolume: ' 13'
isi: 1
issue: '1'
language:
- iso: eng
month: '03'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review X
publication_identifier:
eissn:
- 2160-3308
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Superdiffusive energy transport in kinetically constrained models
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 13
year: '2023'
...
---
_id: '13277'
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.
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. '
article_number: '029'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Gennaro
full_name: Tucci, Gennaro
last_name: Tucci
- first_name: Stefano
full_name: De Nicola, Stefano
id: 42832B76-F248-11E8-B48F-1D18A9856A87
last_name: De Nicola
orcid: 0000-0002-4842-6671
- first_name: Sascha
full_name: Wald, Sascha
last_name: Wald
- first_name: Andrea
full_name: Gambassi, Andrea
last_name: Gambassi
citation:
ama: Tucci G, De Nicola S, Wald S, Gambassi A. Stochastic representation of the
quantum quartic oscillator. SciPost Physics Core. 2023;6(2). doi:10.21468/scipostphyscore.6.2.029
apa: Tucci, G., De Nicola, S., Wald, S., & Gambassi, A. (2023). Stochastic representation
of the quantum quartic oscillator. SciPost Physics Core. SciPost Foundation.
https://doi.org/10.21468/scipostphyscore.6.2.029
chicago: Tucci, Gennaro, Stefano De Nicola, Sascha Wald, and Andrea Gambassi. “Stochastic
Representation of the Quantum Quartic Oscillator.” SciPost Physics Core.
SciPost Foundation, 2023. https://doi.org/10.21468/scipostphyscore.6.2.029.
ieee: G. Tucci, S. De Nicola, S. Wald, and A. Gambassi, “Stochastic representation
of the quantum quartic oscillator,” SciPost Physics Core, vol. 6, no. 2.
SciPost Foundation, 2023.
ista: Tucci G, De Nicola S, Wald S, Gambassi A. 2023. Stochastic representation
of the quantum quartic oscillator. SciPost Physics Core. 6(2), 029.
mla: Tucci, Gennaro, et al. “Stochastic Representation of the Quantum Quartic Oscillator.”
SciPost Physics Core, vol. 6, no. 2, 029, SciPost Foundation, 2023, doi:10.21468/scipostphyscore.6.2.029.
short: G. Tucci, S. De Nicola, S. Wald, A. Gambassi, SciPost Physics Core 6 (2023).
corr_author: '1'
date_created: 2023-07-24T10:47:46Z
date_published: 2023-04-14T00:00:00Z
date_updated: 2025-04-14T07:43:56Z
day: '14'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.21468/scipostphyscore.6.2.029
ec_funded: 1
external_id:
arxiv:
- '2211.01923'
file:
- access_level: open_access
checksum: b472bc82108747eda5d52adf9e2ac7f3
content_type: application/pdf
creator: dernst
date_created: 2023-07-31T09:02:27Z
date_updated: 2023-07-31T09:02:27Z
file_id: '13329'
file_name: 2023_SciPostPhysCore_Tucci.pdf
file_size: 523236
relation: main_file
success: 1
file_date_updated: 2023-07-31T09:02:27Z
has_accepted_license: '1'
intvolume: ' 6'
issue: '2'
keyword:
- Statistical and Nonlinear Physics
- Atomic and Molecular Physics
- and Optics
- Nuclear and High Energy Physics
- Condensed Matter Physics
language:
- iso: eng
month: '04'
oa: 1
oa_version: Published Version
project:
- _id: 260C2330-B435-11E9-9278-68D0E5697425
call_identifier: H2020
grant_number: '754411'
name: ISTplus - Postdoctoral Fellowships
publication: SciPost Physics Core
publication_identifier:
issn:
- 2666-9366
publication_status: published
publisher: SciPost Foundation
quality_controlled: '1'
scopus_import: '1'
status: public
title: Stochastic representation of the quantum quartic oscillator
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 6
year: '2023'
...
---
OA_place: publisher
_id: '12732'
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."
acknowledged_ssus:
- _id: ScienComp
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Pietro
full_name: Brighi, Pietro
id: 4115AF5C-F248-11E8-B48F-1D18A9856A87
last_name: Brighi
orcid: 0000-0002-7969-2729
citation:
ama: Brighi P. Ergodicity breaking in disordered and kinetically constrained quantum
many-body systems. 2023. doi:10.15479/at:ista:12732
apa: Brighi, P. (2023). Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems. Institute of Science and Technology Austria. https://doi.org/10.15479/at:ista:12732
chicago: Brighi, Pietro. “Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems.” Institute of Science and Technology Austria, 2023.
https://doi.org/10.15479/at:ista:12732.
ieee: P. Brighi, “Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems,” Institute of Science and Technology Austria, 2023.
ista: Brighi P. 2023. Ergodicity breaking in disordered and kinetically constrained
quantum many-body systems. Institute of Science and Technology Austria.
mla: Brighi, Pietro. Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems. Institute of Science and Technology Austria, 2023,
doi:10.15479/at:ista:12732.
short: P. Brighi, Ergodicity Breaking in Disordered and Kinetically Constrained
Quantum Many-Body Systems, Institute of Science and Technology Austria, 2023.
corr_author: '1'
date_created: 2023-03-17T13:30:48Z
date_published: 2023-03-21T00:00:00Z
date_updated: 2026-04-07T13:26:32Z
day: '21'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaSe
doi: 10.15479/at:ista:12732
ec_funded: 1
file:
- access_level: closed
checksum: 5d2de651ef9449c1b8dc27148ca74777
content_type: application/zip
creator: pbrighi
date_created: 2023-03-23T16:42:56Z
date_updated: 2023-03-23T16:42:56Z
file_id: '12753'
file_name: Thesis_sub_PBrighi.zip
file_size: 42167561
relation: source_file
- access_level: open_access
checksum: 7caa153d4a5b0873a79358787d2dfe1e
content_type: application/pdf
creator: pbrighi
date_created: 2023-03-23T16:43:14Z
date_updated: 2023-03-23T16:43:14Z
file_id: '12754'
file_name: Thesis_PBrighi.pdf
file_size: 13977000
relation: main_file
success: 1
file_date_updated: 2023-03-23T16:43:14Z
has_accepted_license: '1'
language:
- iso: eng
license: https://creativecommons.org/licenses/by-nc-sa/4.0/
month: '03'
oa: 1
oa_version: Published Version
page: '158'
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '12750'
relation: part_of_dissertation
status: public
- id: '11470'
relation: part_of_dissertation
status: public
- id: '8308'
relation: part_of_dissertation
status: public
- id: '11469'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
title: Ergodicity breaking in disordered and kinetically constrained quantum many-body
systems
tmp:
image: /images/cc_by_nc_sa.png
legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2023'
...
---
OA_place: publisher
_id: '14622'
abstract:
- lang: eng
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."
alternative_title:
- ISTA Thesis
article_processing_charge: No
author:
- first_name: Stefan
full_name: Sack, Stefan
id: dd622248-f6e0-11ea-865d-ce382a1c81a5
last_name: Sack
orcid: 0000-0001-5400-8508
citation:
ama: 'Sack S. Improving variational quantum algorithms : Innovative initialization
techniques and extensions to qudit systems. 2023. doi:10.15479/at:ista:14622'
apa: 'Sack, S. (2023). Improving variational quantum algorithms : Innovative
initialization techniques and extensions to qudit systems. Institute of Science
and Technology Austria. https://doi.org/10.15479/at:ista:14622'
chicago: 'Sack, Stefan. “Improving Variational Quantum Algorithms : Innovative Initialization
Techniques and Extensions to Qudit Systems.” Institute of Science and Technology
Austria, 2023. https://doi.org/10.15479/at:ista:14622.'
ieee: 'S. Sack, “Improving variational quantum algorithms : Innovative initialization
techniques and extensions to qudit systems,” Institute of Science and Technology
Austria, 2023.'
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. Improving Variational Quantum Algorithms : Innovative Initialization
Techniques and Extensions to Qudit Systems. Institute of Science and Technology
Austria, 2023, doi:10.15479/at:ista:14622.'
short: 'S. Sack, Improving Variational Quantum Algorithms : Innovative Initialization
Techniques and Extensions to Qudit Systems, Institute of Science and Technology
Austria, 2023.'
corr_author: '1'
date_created: 2023-11-28T10:58:13Z
date_published: 2023-11-30T00:00:00Z
date_updated: 2026-04-07T13:53:47Z
day: '30'
ddc:
- '530'
degree_awarded: PhD
department:
- _id: GradSch
- _id: MaSe
doi: 10.15479/at:ista:14622
ec_funded: 1
file:
- access_level: open_access
checksum: 068fd3570506ec42b2faa390de784bc4
content_type: application/pdf
creator: ssack
date_created: 2023-11-30T15:53:10Z
date_updated: 2024-11-30T23:30:03Z
embargo: 2024-11-30
file_id: '14635'
file_name: PhD_Thesis.pdf
file_size: 11947523
relation: main_file
- access_level: closed
checksum: 0fa3bc0d108aed0ac59d2c6beef2220a
content_type: application/zip
creator: ssack
date_created: 2023-11-30T15:54:11Z
date_updated: 2024-11-30T23:30:03Z
embargo_to: open_access
file_id: '14636'
file_name: PhD Thesis (1).zip
file_size: 18422964
relation: source_file
file_date_updated: 2024-11-30T23:30:03Z
has_accepted_license: '1'
language:
- iso: eng
month: '11'
oa: 1
oa_version: Published Version
page: '142'
project:
- _id: bd660c93-d553-11ed-ba76-fb0fb6f49c0d
name: IMB PhD Nomination Fellowship - Stefan Sack
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication_identifier:
issn:
- 2663-337X
publication_status: published
publisher: Institute of Science and Technology Austria
related_material:
record:
- id: '13125'
relation: part_of_dissertation
status: public
- id: '11471'
relation: part_of_dissertation
status: public
- id: '9760'
relation: part_of_dissertation
status: public
status: public
supervisor:
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
title: 'Improving variational quantum algorithms : Innovative initialization techniques
and extensions to qudit systems'
tmp:
image: /images/cc_by_nc_sa.png
legal_code_url: https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode
name: Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC
BY-NC-SA 4.0)
short: CC BY-NC-SA (4.0)
type: dissertation
user_id: ba8df636-2132-11f1-aed0-ed93e2281fdd
year: '2023'
...
---
_id: '13125'
abstract:
- lang: eng
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. '
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). '
article_number: '062404'
article_processing_charge: No
article_type: original
arxiv: 1
author:
- first_name: Stefan
full_name: Sack, Stefan
id: dd622248-f6e0-11ea-865d-ce382a1c81a5
last_name: Sack
orcid: 0000-0001-5400-8508
- first_name: Raimel A
full_name: Medina Ramos, Raimel A
id: CE680B90-D85A-11E9-B684-C920E6697425
last_name: Medina Ramos
orcid: 0000-0002-5383-2869
- first_name: Richard
full_name: Kueng, Richard
last_name: Kueng
- first_name: Maksym
full_name: Serbyn, Maksym
id: 47809E7E-F248-11E8-B48F-1D18A9856A87
last_name: Serbyn
orcid: 0000-0002-2399-5827
citation:
ama: Sack S, Medina Ramos RA, Kueng R, Serbyn M. Recursive greedy initialization
of the quantum approximate optimization algorithm with guaranteed improvement.
Physical Review A. 2023;107(6). doi:10.1103/physreva.107.062404
apa: Sack, S., Medina Ramos, R. A., Kueng, R., & Serbyn, M. (2023). Recursive
greedy initialization of the quantum approximate optimization algorithm with guaranteed
improvement. Physical Review A. American Physical Society. https://doi.org/10.1103/physreva.107.062404
chicago: Sack, Stefan, Raimel A Medina Ramos, Richard Kueng, and Maksym Serbyn.
“Recursive Greedy Initialization of the Quantum Approximate Optimization Algorithm
with Guaranteed Improvement.” Physical Review A. American Physical Society,
2023. https://doi.org/10.1103/physreva.107.062404.
ieee: S. Sack, R. A. Medina Ramos, R. Kueng, and M. Serbyn, “Recursive greedy initialization
of the quantum approximate optimization algorithm with guaranteed improvement,”
Physical Review A, vol. 107, no. 6. American Physical Society, 2023.
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.
mla: Sack, Stefan, et al. “Recursive Greedy Initialization of the Quantum Approximate
Optimization Algorithm with Guaranteed Improvement.” Physical Review A,
vol. 107, no. 6, 062404, American Physical Society, 2023, doi:10.1103/physreva.107.062404.
short: S. Sack, R.A. Medina Ramos, R. Kueng, M. Serbyn, Physical Review A 107 (2023).
corr_author: '1'
date_created: 2023-06-07T06:57:32Z
date_published: 2023-06-02T00:00:00Z
date_updated: 2026-04-23T22:30:22Z
day: '02'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/physreva.107.062404
ec_funded: 1
external_id:
arxiv:
- '2209.01159'
isi:
- '001016927100012'
file:
- access_level: open_access
checksum: 0d71423888eeccaa60d8f41197f26306
content_type: application/pdf
creator: dernst
date_created: 2023-06-13T07:28:36Z
date_updated: 2023-06-13T07:28:36Z
file_id: '13131'
file_name: 2023_PhysRevA_Sack.pdf
file_size: 2524611
relation: main_file
success: 1
file_date_updated: 2023-06-13T07:28:36Z
has_accepted_license: '1'
intvolume: ' 107'
isi: 1
issue: '6'
language:
- iso: eng
month: '06'
oa: 1
oa_version: Published Version
project:
- _id: 23841C26-32DE-11EA-91FC-C7463DDC885E
call_identifier: H2020
grant_number: '850899'
name: 'Non-Ergodic Quantum Matter: Universality, Dynamics and Control'
publication: Physical Review A
publication_identifier:
eissn:
- 2469-9934
issn:
- 2469-9926
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
related_material:
record:
- id: '17208'
relation: dissertation_contains
status: public
- id: '14622'
relation: dissertation_contains
status: public
scopus_import: '1'
status: public
title: Recursive greedy initialization of the quantum approximate optimization algorithm
with guaranteed improvement
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 4359f0d1-fa6c-11eb-b949-802e58b17ae8
volume: 107
year: '2023'
...
---
_id: '12111'
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.
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].
article_number: '043177'
article_processing_charge: No
article_type: original
author:
- first_name: Lidia
full_name: Stocker, Lidia
last_name: Stocker
- first_name: Stefan
full_name: Sack, Stefan
id: dd622248-f6e0-11ea-865d-ce382a1c81a5
last_name: Sack
- first_name: Michael S.
full_name: Ferguson, Michael S.
last_name: Ferguson
- first_name: Oded
full_name: Zilberberg, Oded
last_name: Zilberberg
citation:
ama: Stocker L, Sack S, Ferguson MS, Zilberberg O. Entanglement-based observables
for quantum impurities. Physical Review Research. 2022;4(4). doi:10.1103/PhysRevResearch.4.043177
apa: Stocker, L., Sack, S., Ferguson, M. S., & Zilberberg, O. (2022). Entanglement-based
observables for quantum impurities. Physical Review Research. American
Physical Society. https://doi.org/10.1103/PhysRevResearch.4.043177
chicago: Stocker, Lidia, Stefan Sack, Michael S. Ferguson, and Oded Zilberberg.
“Entanglement-Based Observables for Quantum Impurities.” Physical Review Research.
American Physical Society, 2022. https://doi.org/10.1103/PhysRevResearch.4.043177.
ieee: L. Stocker, S. Sack, M. S. Ferguson, and O. Zilberberg, “Entanglement-based
observables for quantum impurities,” Physical Review Research, vol. 4,
no. 4. American Physical Society, 2022.
ista: Stocker L, Sack S, Ferguson MS, Zilberberg O. 2022. Entanglement-based observables
for quantum impurities. Physical Review Research. 4(4), 043177.
mla: Stocker, Lidia, et al. “Entanglement-Based Observables for Quantum Impurities.”
Physical Review Research, vol. 4, no. 4, 043177, American Physical Society,
2022, doi:10.1103/PhysRevResearch.4.043177.
short: L. Stocker, S. Sack, M.S. Ferguson, O. Zilberberg, Physical Review Research
4 (2022).
date_created: 2023-01-08T23:00:53Z
date_published: 2022-12-01T00:00:00Z
date_updated: 2023-02-13T09:08:28Z
day: '01'
ddc:
- '530'
department:
- _id: MaSe
doi: 10.1103/PhysRevResearch.4.043177
file:
- access_level: open_access
checksum: 556820cf6e4af77c8476e5b8f4114d1a
content_type: application/pdf
creator: dernst
date_created: 2023-01-20T12:03:31Z
date_updated: 2023-01-20T12:03:31Z
file_id: '12328'
file_name: 2022_PhysicalReviewResearch_Stocker.pdf
file_size: 2941167
relation: main_file
success: 1
file_date_updated: 2023-01-20T12:03:31Z
has_accepted_license: '1'
intvolume: ' 4'
issue: '4'
language:
- iso: eng
month: '12'
oa: 1
oa_version: Published Version
publication: Physical Review Research
publication_identifier:
issn:
- 2643-1564
publication_status: published
publisher: American Physical Society
quality_controlled: '1'
scopus_import: '1'
status: public
title: Entanglement-based observables for quantum impurities
tmp:
image: /images/cc_by.png
legal_code_url: https://creativecommons.org/licenses/by/4.0/legalcode
name: Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)
short: CC BY (4.0)
type: journal_article
user_id: 2DF688A6-F248-11E8-B48F-1D18A9856A87
volume: 4
year: '2022'
...