[{"page":"97","supervisor":[{"orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink","first_name":"Johannes M","full_name":"Fink, Johannes M"}],"type":"dissertation","abstract":[{"text":"Atoms and photons, two things so different but yet so alike. The former, the building block of matter, something we learn about in school and imagine it as some tiny marbles encircled by other tinier marbles. The latter, an electromagnetic wave, a light particle or an excitation of the electromagnetic field. Quantum mechanics tells us about the properties of these two entities. And even if it sounds, looks and writes counter-intuitive, it has proven right for over a century now.\r\n\r\nIn this work, I elaborate on how we tested the laws of quantum mechanics and how we used them learn more about the tiny building blocks of nature and the fields they use to talk to each other. The atoms we use, are artificial. Superconducting qubits, small electrical circuits with quantized energy levels behave like electrons that transition between different orbitals in an atom. One of the qubits' advantages, is also a big disadvantage. We design the circuits' energy levels and fabricate them in a cleanroom. This allows for arbitrary spaced energy levels but in contrast to real atoms, prevents two superconducting qubits from being alike. Still, this qubit platform is one of the frontrunners for future quantum computing technology and testing fundamental physics due to their scalability.\r\n\r\nWe interface superconducting qubits, which operate in the GHz regime, with microwave photons. We use 3D aluminum cavities as mediators between qubits and photons. The cavities allow for non-destructive readout of the qubit state, they shield the qubits from noise at the qubit frequency and they give us an easy way to frequency-tune these joint systems.\r\n\r\nWe need to operate superconducting qubits and their cavities at millikelvin temperatures in dilution refrigerators. At higher temperatures, superconductivity suffers and even worse, the environment is filled with thermal noise photons. This poses a fundamental limitation on the scalability of superconducting qubit devices. Also connecting multiple devices in different fridges does not work over room temperature links because the microwave photons used for this purpose will be covered in noise and the quantum information they carry, will be unusable.\r\n\r\nInfrared photons do not suffer from this noise problem since there are close to zero thermal noise photons at their frequencies at room temperature. We cannot simply interface superconducting devices with optical photons due their frequency mismatch and the destructive effect of optical photons on superconductors. Therefore, we use microwave-to-optics transducers that allow to convert microwave photons into optical ones and vice-versa. The transducers that we use are macroscopic electro-optic transducers using the Pockels effect in a disk-shaped Lithium Niobate whispering gallery mode resonator. By using a strong optical pump, photons from the two frequency domains experience a beam-splitter interaction and get converted from one to the other.\r\n\r\nWe measure the generated optical photons using elaborate optical setups, optical heterodyning and single photon detectors to gain knowledge about the qubit state or the converted microwave photons. Bridging the microwave and the optical world allows us to take advantage of both of their strengths but it also requires deep knowledge about both of their working principles.\r\n\r\nIn this work, we describe two experiments that our group conducted to showcase the opportunities that arise from interfacing superconducting qubits with optical photons but also the pitfalls, one may encounter on the way.\r\n\r\nIn the first experiment, we managed to all-optically read out a superconducting qubit. We show that the assignment fidelity, the probability that a measurement of the qubit state matches the prepared state, is close to equal for all-optical, microwave-to-optics and conventional microwave readout. We show T1 and T2 measurements for all three readout types and give an analysis of the noise caused by the optics. Finally, we show that the infrared light does not affect the qubit performance in a negative way but that the heating it causes does. This is an important insight that we used in the next experiment.\r\n\r\nThe second experiment is the upconversion of itinerant single microwave photons to the optical domain. We show that we can generate single microwave photons from a qubit-cavity system. We upconvert these single photons, measure them with a single photon detector and reconstruct their shape. By conducting a single photon Rabi measurement, we show correlations between the microwave and the optical domain. And by thorough signal-to-noise measurements and noise analysis, we find that we can generate single infrared photons with high signal-to-noise ratio 5.1 and low transducer added noise (<0.012 quanta). We show that this measurement creates a path towards entanglement of a superconducting qubit and an optical photon and what parameters need to be improved to achieve it. Additionally, this experiment is a proof of principle for an on-demand infrared single photon source. More generally, it allows to link microwave quantum technology in general to the optical domain.","lang":"eng"}],"ddc":["530","537","539"],"department":[{"_id":"GradSch"},{"_id":"JoFi"}],"doi":"10.15479/AT-ISTA-21863","oa_version":"Published Version","OA_place":"publisher","publisher":"Institute of Science and Technology Austria","citation":{"ama":"Werner T. Interfacing superconducting qubits with optical photons. 2026. doi:<a href=\"https://doi.org/10.15479/AT-ISTA-21863\">10.15479/AT-ISTA-21863</a>","ieee":"T. Werner, “Interfacing superconducting qubits with optical photons,” Institute of Science and Technology Austria, 2026.","ista":"Werner T. 2026. Interfacing superconducting qubits with optical photons. Institute of Science and Technology Austria.","apa":"Werner, T. (2026). <i>Interfacing superconducting qubits with optical photons</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/AT-ISTA-21863\">https://doi.org/10.15479/AT-ISTA-21863</a>","chicago":"Werner, Thomas. “Interfacing Superconducting Qubits with Optical Photons.” Institute of Science and Technology Austria, 2026. <a href=\"https://doi.org/10.15479/AT-ISTA-21863\">https://doi.org/10.15479/AT-ISTA-21863</a>.","short":"T. Werner, Interfacing Superconducting Qubits with Optical Photons, Institute of Science and Technology Austria, 2026.","mla":"Werner, Thomas. <i>Interfacing Superconducting Qubits with Optical Photons</i>. Institute of Science and Technology Austria, 2026, doi:<a href=\"https://doi.org/10.15479/AT-ISTA-21863\">10.15479/AT-ISTA-21863</a>."},"user_id":"8b945eb4-e2f2-11eb-945a-df72226e66a9","author":[{"orcid":"0009-0001-2346-5236","last_name":"Werner","id":"1fcd8497-dba3-11ea-a45e-c6fbd715f7c7","full_name":"Werner, Thomas","first_name":"Thomas"}],"date_published":"2026-05-12T00:00:00Z","title":"Interfacing superconducting qubits with optical photons","status":"public","has_accepted_license":"1","acknowledgement":"The author of this work was supported by the European Research Council under grant no.\r\n101089099 (ERC CoG cQEO) and the European Union’s Horizon 2020 research and innovation\r\nprogram under grant no. 899354 (FETopen SuperQuLAN).\r\nThis work was also supported by the European Research Council under grant nos. 758053\r\n(ERC StG QUNNECT), 101248662 (ERC POC CoupledEOT), and the European Innovation\r\nCouncil no. 101187231 (PathfinderOpen CIELO). This research was funded in whole or in part\r\nby the Austrian Science Fund (FWF) [10.55776/F71]. For open access purposes, the author\r\nhas applied a CC BY public copyright license to any author accepted manuscript version arising\r\nfrom this submission.\r\niii\r\nMy co-authors in the works mentioned later acknowledge generous support from the ISTFELLOW program, the NOMIS-ISTA fellowship, the Horizon Europe Program HORIZONCL4-2022-QUANTUM-01-SGA via Project No. 101113946 OpenSuperQPlus100 and a DOC fellowship of the Austrian Academy of Sciences at IST Austria.\r\n","oa":1,"degree_awarded":"PhD","file_date_updated":"2026-05-15T15:54:06Z","publication_status":"published","date_updated":"2026-05-20T13:35:43Z","month":"05","acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"NanoFab"},{"_id":"LifeSc"},{"_id":"SSU"}],"year":"2026","date_created":"2026-05-12T09:04:02Z","language":[{"iso":"eng"}],"_id":"21863","day":"12","keyword":["Superconducting qubits","Quantum optics","Single photons and quantum effects","Nonlinear optics"],"related_material":{"record":[{"relation":"part_of_dissertation","status":"public","id":"19073"},{"relation":"part_of_dissertation","status":"public","id":"21870"}]},"corr_author":"1","tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"file":[{"relation":"main_file","file_size":9330516,"date_created":"2026-05-15T15:53:57Z","access_level":"open_access","content_type":"application/pdf","checksum":"a5b4d8dba83f96e955a3625c0eebee98","file_name":"2026_Werner_Thomas_Thesis.pdf","date_updated":"2026-05-15T15:53:57Z","creator":"twerner","file_id":"21879"},{"file_id":"21880","creator":"twerner","date_updated":"2026-05-15T15:54:06Z","file_name":"2026_Werner_Thomas_Thesis.zip","content_type":"application/x-zip-compressed","checksum":"b41282beaacfb32472769b9e3b1758d8","access_level":"closed","file_size":9370704,"date_created":"2026-05-15T15:54:06Z","relation":"source_file"}],"publication_identifier":{"issn":["2663-337X"]},"ec_funded":1,"article_processing_charge":"No","project":[{"_id":"bdadfa0d-d553-11ed-ba76-fb85edbd456a","grant_number":"101089099","name":"Cavity Quantum Electro Optics: Microwave photonics with nonclassical states"},{"name":"Quantum Local Area Networks with Superconducting Qubits","call_identifier":"H2020","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354"},{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"name":"Integrated optical coupling for low loss electro-optic interconnects","grant_number":"101248662","_id":"5b807754-ab3d-11f0-914f-ff8c34502cc9"},{"name":"Cavity-Integrated Electro-Optics: Measuring, Converting and Manipulating Microwaves with Light","_id":"91aaf765-16d5-11f0-9cad-a8e7e44cccb7","grant_number":"101187231"},{"name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits","grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f"},{"name":"Open Superconducting Quantum Computers (OpenSuperQPlus)","_id":"bdb7cfc1-d553-11ed-ba76-d2eaab167738","grant_number":"101080139"},{"_id":"9B861AAC-BA93-11EA-9121-9846C619BF3A","name":"NOMIS Fellowship Program"}],"alternative_title":["ISTA Thesis"]},{"acknowledgement":"We thank Fritz Diorico and Onur Hosten who suggested the filter cavity design, and gave important insights about the assembly and the testing of the FabryPerot filter cavities. Ekatrina Fedotova and Diego A.\r\nLancheros Naranjo worked on the filter cavity setup in\r\nthe early stages of this work. Gustavo Wiederhecker and\r\nYiewen Chu provided insights as to the origins of the\r\nobserved optical noise and Nicola Carlon Zambon suggested using telecom filters to mitigate it further. This\r\nwork was supported by the European Research Council under grant agreement no. 101089099 (ERC CoG\r\ncQEO), and 101248662 (ERC POC CoupledEOT), the\r\nEuropean Unions Horizon 2020 research and innovation\r\nprogram under grant agreement no. 899354 (FETopen\r\nSuperQuLAN), the European Innovation Council no.\r\n101187231 (PathfinderOpen CIELO), and the Austrian\r\nScience Fund (FWF) no. F7105 (SFB BeyondC). J.F.\r\nand L.K. acknowledge support from the Horizon Europe\r\nProgram HORIZON-CL4-2022-QUANTUM-01-SGA via\r\nProject No. 101113946 OpenSuperQPlus100. A.M. acknowledges support from the NOMIS-ISTA fellowship.","oa":1,"publication_status":"draft","date_updated":"2026-05-20T13:35:42Z","arxiv":1,"month":"01","publication":"arXiv","OA_type":"green","abstract":[{"lang":"eng","text":"Superconducting qubits are a leading candidate for utility-scale quantum computing due to their fast gate speeds and steadily decreasing error rates. The requirement for millikelvin operating temperatures, however, creates a significant scaling bottleneck. Modular architectures using optical fiber links could bridge separate cryogenic nodes, but superconducting circuits do not have coherent optical transitions and microwave-to-optical conversion has not been shown for any non-classical photon state. In this work, we demonstrate the on-demand generation and tomographic reconstruction of itinerant single microwave photons at 8.9 GHz from a superconducting qubit. We upconvert this non-Gaussian state with a transducer added noise below 0.012 quanta and count the converted telecom photons at 193.4 THz with a signal-to-noise ratio of up to 5.1$\\pm$1.1. We characterize the trade-offs between throughput and noise, and establish a viable path toward heralded entanglement distribution and gate teleportation. Looking ahead, these results empower existing superconducting devices to take a key role in distributed quantum technologies and heterogeneous quantum systems."}],"type":"preprint","department":[{"_id":"JoFi"},{"_id":"GradSch"}],"doi":"10.48550/arXiv.2602.00928","oa_version":"Preprint","OA_place":"repository","user_id":"8b945eb4-e2f2-11eb-945a-df72226e66a9","citation":{"apa":"Werner, T., Riyazi, E., Hawaldar, S., Sahu, R., Arnold, G. M., Paul Falthansl-Scheinecker, P. F.-S., … Fink, J. M. (n.d.). Electro-optic conversion of itinerant Fock states. <i>arXiv</i>. <a href=\"https://doi.org/10.48550/arXiv.2602.00928\">https://doi.org/10.48550/arXiv.2602.00928</a>","ista":"Werner T, Riyazi E, Hawaldar S, Sahu R, Arnold GM, Paul Falthansl-Scheinecker PF-S, Naranjo JAS, Loi D, Kapoor LN, Zemlicka M, Qiu L, Militaru A, Fink JM. Electro-optic conversion of itinerant Fock states. arXiv, <a href=\"https://doi.org/10.48550/arXiv.2602.00928\">10.48550/arXiv.2602.00928</a>.","ieee":"T. Werner <i>et al.</i>, “Electro-optic conversion of itinerant Fock states,” <i>arXiv</i>. .","ama":"Werner T, Riyazi E, Hawaldar S, et al. Electro-optic conversion of itinerant Fock states. <i>arXiv</i>. doi:<a href=\"https://doi.org/10.48550/arXiv.2602.00928\">10.48550/arXiv.2602.00928</a>","short":"T. Werner, E. Riyazi, S. Hawaldar, R. Sahu, G.M. Arnold, P.F.-S. Paul Falthansl-Scheinecker, J.A.S. Naranjo, D. Loi, L.N. Kapoor, M. Zemlicka, L. Qiu, A. Militaru, J.M. Fink, ArXiv (n.d.).","mla":"Werner, Thomas, et al. “Electro-Optic Conversion of Itinerant Fock States.” <i>ArXiv</i>, doi:<a href=\"https://doi.org/10.48550/arXiv.2602.00928\">10.48550/arXiv.2602.00928</a>.","chicago":"Werner, Thomas, Erfan Riyazi, Samarth Hawaldar, Rishabh Sahu, Georg M Arnold, Paul Falthansl-Scheinecker Paul Falthansl-Scheinecker, Jennifer A. Sánchez Naranjo, et al. “Electro-Optic Conversion of Itinerant Fock States.” <i>ArXiv</i>, n.d. <a href=\"https://doi.org/10.48550/arXiv.2602.00928\">https://doi.org/10.48550/arXiv.2602.00928</a>."},"author":[{"full_name":"Werner, Thomas","first_name":"Thomas","orcid":"0009-0001-2346-5236","id":"1fcd8497-dba3-11ea-a45e-c6fbd715f7c7","last_name":"Werner"},{"last_name":"Riyazi","id":"53322f94-5355-11ee-ae5a-ff6f81c87d51","first_name":"Erfan","full_name":"Riyazi, Erfan"},{"first_name":"Samarth","full_name":"Hawaldar, Samarth","id":"221708e1-1ff6-11ee-9fa6-85146607433e","last_name":"Hawaldar","orcid":"0000-0002-1965-4309"},{"id":"47D26E34-F248-11E8-B48F-1D18A9856A87","last_name":"Sahu","orcid":"0000-0001-6264-2162","full_name":"Sahu, Rishabh","first_name":"Rishabh"},{"id":"3770C838-F248-11E8-B48F-1D18A9856A87","last_name":"Arnold","orcid":"0000-0003-1397-7876","first_name":"Georg M","full_name":"Arnold, Georg M"},{"last_name":"Paul Falthansl-Scheinecker","first_name":"Paul Falthansl-Scheinecker","full_name":"Paul Falthansl-Scheinecker, Paul Falthansl-Scheinecker"},{"last_name":"Naranjo","first_name":"Jennifer A. Sánchez","full_name":"Naranjo, Jennifer A. Sánchez"},{"full_name":"Loi, Dante","first_name":"Dante","last_name":"Loi"},{"first_name":"Lucky N.","full_name":"Kapoor, Lucky N.","last_name":"Kapoor"},{"first_name":"Martin","full_name":"Zemlicka, Martin","orcid":"0009-0005-0878-3032","id":"2DCF8DE6-F248-11E8-B48F-1D18A9856A87","last_name":"Zemlicka"},{"full_name":"Qiu, Liu","first_name":"Liu","orcid":"0000-0003-4345-4267","last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac"},{"full_name":"Militaru, Andrei","first_name":"Andrei","last_name":"Militaru","id":"d67706f8-8eb1-11ee-ad1b-9c30dfa19e0b"},{"full_name":"Fink, Johannes M","first_name":"Johannes M","orcid":"0000-0001-8112-028X","last_name":"Fink","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87"}],"external_id":{"arxiv":["2602.00928"]},"date_published":"2026-01-31T00:00:00Z","title":"Electro-optic conversion of itinerant Fock states","status":"public","scopus_import":"1","ec_funded":1,"article_processing_charge":"No","project":[{"_id":"bdadfa0d-d553-11ed-ba76-fb85edbd456a","grant_number":"101089099","name":"Cavity Quantum Electro Optics: Microwave photonics with nonclassical states"},{"name":"Integrated optical coupling for low loss electro-optic interconnects","_id":"5b807754-ab3d-11f0-914f-ff8c34502cc9","grant_number":"101248662"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","name":"Quantum Local Area Networks with Superconducting Qubits","call_identifier":"H2020"},{"name":"Cavity-Integrated Electro-Optics: Measuring, Converting and Manipulating Microwaves with Light","grant_number":"101187231","_id":"91aaf765-16d5-11f0-9cad-a8e7e44cccb7"},{"call_identifier":"FWF","name":"Integrating superconducting quantum circuits","_id":"26927A52-B435-11E9-9278-68D0E5697425","grant_number":"F07105"},{"name":"NOMIS Fellowship Program","_id":"9B861AAC-BA93-11EA-9121-9846C619BF3A"}],"main_file_link":[{"open_access":"1","url":"https://doi.org/10.48550/arXiv.2602.00928"}],"date_created":"2026-05-12T13:58:18Z","year":"2026","language":[{"iso":"eng"}],"_id":"21870","day":"31","corr_author":"1","related_material":{"record":[{"status":"public","relation":"dissertation_contains","id":"21863"}]},"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"}},{"project":[{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"_id":"bdadfa0d-d553-11ed-ba76-fb85edbd456a","grant_number":"101089099","name":"Cavity Quantum Electro Optics: Microwave photonics with nonclassical states"},{"grant_number":"899354","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"_id":"2671EB66-B435-11E9-9278-68D0E5697425","name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies"},{"grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"}],"article_processing_charge":"Yes (via OA deal)","ec_funded":1,"scopus_import":"1","publication_identifier":{"eissn":["1745-2481"],"issn":["1745-2473"]},"_id":"19073","language":[{"iso":"eng"}],"intvolume":"        21","day":"01","corr_author":"1","related_material":{"link":[{"url":"https://ista.ac.at/en/news/when-qubits-learn-the-language-of-fiberoptics/","description":"News on ISTA Website","relation":"press_release"}],"record":[{"relation":"earlier_version","status":"public","id":"18953"},{"id":"21863","relation":"dissertation_contains","status":"public"}]},"file":[{"file_id":"19572","success":1,"creator":"dernst","date_updated":"2025-04-16T08:09:43Z","file_name":"2025_NaturePhysics_Arnold.pdf","checksum":"ab7469aca9e2e068eb78e5c5c1efaf7d","content_type":"application/pdf","access_level":"open_access","file_size":3396595,"date_created":"2025-04-16T08:09:43Z","relation":"main_file"}],"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"date_created":"2025-02-23T23:01:57Z","year":"2025","isi":1,"quality_controlled":"1","month":"03","publication":"Nature Physics","date_updated":"2026-05-20T13:35:42Z","volume":21,"oa":1,"file_date_updated":"2025-04-16T08:09:43Z","publication_status":"published","acknowledgement":"We thank F. Hassani and M. Zemlicka for assistance with qubit design and high-power readout, respectively, and P. Winkel and I. Pop at Karlsruhe Institute of Technology for providing the JPA. This work was supported by the European Research Council under grant nos. 758053 (ERC StG QUNNECT) and 101089099 (ERC CoG cQEO), and the European Union’s Horizon 2020 research and innovation program under grant no. 899354 (FETopen SuperQuLAN). This research was funded in whole, or in part, by the Austrian Science Fund (FWF) DOI 10.55776/F71. L.Q. acknowledges generous support from the ISTFELLOW programme and G.A. is the recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria. Open access funding provided by Institute of Science and Technology (IST Austria).","has_accepted_license":"1","external_id":{"pmid":["40093969"],"isi":["001417760400001"]},"date_published":"2025-03-01T00:00:00Z","title":"All-optical superconducting qubit readout","article_number":"9470","status":"public","pmid":1,"doi":"10.1038/s41567-024-02741-4","oa_version":"Published Version","OA_place":"publisher","publisher":"Springer Nature","user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","citation":{"mla":"Arnold, Georg M., et al. “All-Optical Superconducting Qubit Readout.” <i>Nature Physics</i>, vol. 21, 9470, Springer Nature, 2025, doi:<a href=\"https://doi.org/10.1038/s41567-024-02741-4\">10.1038/s41567-024-02741-4</a>.","short":"G.M. Arnold, T. Werner, R. Sahu, L. Kapoor, L. Qiu, J.M. Fink, Nature Physics 21 (2025).","chicago":"Arnold, Georg M, Thomas Werner, Rishabh Sahu, Lucky Kapoor, Liu Qiu, and Johannes M Fink. “All-Optical Superconducting Qubit Readout.” <i>Nature Physics</i>. Springer Nature, 2025. <a href=\"https://doi.org/10.1038/s41567-024-02741-4\">https://doi.org/10.1038/s41567-024-02741-4</a>.","apa":"Arnold, G. M., Werner, T., Sahu, R., Kapoor, L., Qiu, L., &#38; Fink, J. M. (2025). All-optical superconducting qubit readout. <i>Nature Physics</i>. Springer Nature. <a href=\"https://doi.org/10.1038/s41567-024-02741-4\">https://doi.org/10.1038/s41567-024-02741-4</a>","ista":"Arnold GM, Werner T, Sahu R, Kapoor L, Qiu L, Fink JM. 2025. All-optical superconducting qubit readout. Nature Physics. 21, 9470.","ieee":"G. M. Arnold, T. Werner, R. Sahu, L. Kapoor, L. Qiu, and J. M. Fink, “All-optical superconducting qubit readout,” <i>Nature Physics</i>, vol. 21. Springer Nature, 2025.","ama":"Arnold GM, Werner T, Sahu R, Kapoor L, Qiu L, Fink JM. All-optical superconducting qubit readout. <i>Nature Physics</i>. 2025;21. doi:<a href=\"https://doi.org/10.1038/s41567-024-02741-4\">10.1038/s41567-024-02741-4</a>"},"author":[{"orcid":"0000-0003-1397-7876","last_name":"Arnold","id":"3770C838-F248-11E8-B48F-1D18A9856A87","full_name":"Arnold, Georg M","first_name":"Georg M"},{"first_name":"Thomas","full_name":"Werner, Thomas","last_name":"Werner","id":"1fcd8497-dba3-11ea-a45e-c6fbd715f7c7","orcid":"0009-0001-2346-5236"},{"orcid":"0000-0001-6264-2162","last_name":"Sahu","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","first_name":"Rishabh","full_name":"Sahu, Rishabh"},{"orcid":"0000-0001-8319-2148","id":"84b9700b-15b2-11ec-abd3-831089e67615","last_name":"Kapoor","full_name":"Kapoor, Lucky","first_name":"Lucky"},{"last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac","orcid":"0000-0003-4345-4267","full_name":"Qiu, Liu","first_name":"Liu"},{"full_name":"Fink, Johannes M","first_name":"Johannes M","orcid":"0000-0001-8112-028X","last_name":"Fink","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87"}],"type":"journal_article","abstract":[{"text":"The rapid development of superconducting quantum hardware is expected to run into substantial restrictions on scalability because error correction in a cryogenic environment has stringent input–output requirements. Classical data centres rely on fibre-optic interconnects to remove similar networking bottlenecks. In the same spirit, ultracold electro-optic links have been proposed and used to generate qubit control signals, or to replace cryogenic readout electronics. So far, these approaches have suffered from either low efficiency, low bandwidth or additional noise. Here we realize radio-over-fibre qubit readout at millikelvin temperatures. We use one device to simultaneously perform upconversion and downconversion between microwave and optical frequencies and so do not require any active or passive cryogenic microwave equipment. We demonstrate all-optical single-shot readout in a circulator-free readout scheme. Importantly, we do not observe any direct radiation impact on the qubit state, despite the absence of shielding elements. This compatibility between superconducting circuits and telecom-wavelength light is not only a prerequisite to establish modular quantum networks, but it is also relevant for multiplexed readout of superconducting photon detectors and classical superconducting logic.","lang":"eng"}],"ddc":["530"],"department":[{"_id":"JoFi"}],"OA_type":"hybrid","article_type":"original"},{"type":"dissertation","abstract":[{"text":"\"Can we do this with a new type of computer - a quantum computer?\". This famous\r\nquotation of the brilliant Richard Feynman within a conference talk on \"Simulating physics\r\nwith computers.” is often reverently praised as the origin of the field of quantum computing.\r\nThe idea was to use quantum mechanical systems itself to simulate \"Nature\", which is\r\ninherently quantum mechanical. Now, 43 years later, the theoretical framework of how such\r\na computer can operate has been developed. Two main important concepts for a potential\r\nquantum supremacy, superposition and entanglement, have been exploited to design quantum\r\nalgorithms to significantly speed up certain tasks. Yet, the specific hardware implementation\r\nis still far from being certain, in fact the race between the most promising platforms such as\r\nsuperconducting qubits, bosonic codes, cold atoms, trapped ions, optical computing as well\r\nas spin qubits has recently intensified. If one also includes the most mature applications of\r\nquantum communication technologies, secure quantum key distribution and quantum random\r\nnumber generators, as part of a quantum information technology ecosystem, we are confronted\r\nwith a plethora of different materials, concepts, and also operation frequencies. While\r\nsuperconducting qubits, bosonic codes and spin qubits work in the regime of approximately 5\r\nGHz and are controlled by electrical fields, trapped ions, cold atoms, and optical quantum\r\ncomputing operate with light in the infrared or visible range.\r\nConsequently, a quantum frequency converter or microwave-optic transducer is required\r\nto interface the different frequency domains or establish a long-range network connection\r\nwith suitable telecom fibers. In fact, the combination of different frequency regimes is also\r\nan essential part in our classical modern communication network, where computations are\r\nperformed in electrical circuits and the information exchange over longer distances happens\r\nvia optical fibers. However, the specific challenges specific to building a quantum computer,\r\nalso apply to the development of such a quantum frequency transducer: 1) As we deal with\r\nsingle excitations as the carrier of information, i.e. the smallest possible quantity, the signal\r\ncan easily be corrupted by other noise sources which needs to be avoided by all means. This\r\nis also the reason why microwave quantum computers operate at temperature environments\r\nclose to zero temperature (< 0.1 Kelvin) to avoid corruption by thermal noise. 2) The\r\nfrequency interface generally needs to preserve the phase of the signal as an essential part\r\nof the quantum state. And 3) Quantum signals cannot be copied which would be a typical\r\nstrategy to account for errors in classical computers. And finally, there is a challenge specific to\r\nmicrowave-optic transducers: While quantum computers are operating in one specific frequency\r\ndomain, microwave-optic transducers combine microwave and optical fields in one device.\r\nThis results in the particular challenge that high-energy optical radiation, which is usually\r\nwell-shielded from superconducting microwave quantum processors, are now an essential part\r\nof the device. The concomitant optical radiation in the operating transducer will inevitably\r\nhave a detrimental effect on the superconducting microwave components. Together with the\r\nrequirement of minimal background noise for quantum-limited operation as described above,\r\nv\r\nheating from the absorption of optical photons within the same device where single microwave\r\nexcitations are processed forms a formidable challenge.\r\nThis thesis aims to address this challenge by developing microwave-optic transducers where\r\nthe impact of optical absorption on superconducting circuits in general and superconducting\r\nqubits specifically can be mitigated. In our first approach, we developed a compact device\r\nwith optimized interaction strengths between the different frequency domains. This minimizes\r\nthe optical powers used for transducer operation and thus the optical absorption heating. This\r\nwork was - to the best of our knowledge - the first comprehensive noise study, in an integrated\r\nmicrowave-optic transducer. Unfortunately, we saw that the optical absorption heating added\r\nnoise way above a single excitation. Consequently, a potential quantum signal would have\r\nbeen buried in the noise, added by the transduction.\r\nBuilding on this insight, we utilized a three-dimensional microwave-optic transducer instead\r\nof an integrated device. The larger heat capacity of the macroscopic device with a size\r\nof a few millimeters can absorb a larger fraction of the optical heating before it increases\r\nthe temperature of the device. This allowed us to interface the transducer directly with a\r\nsuperconducting qubit to readout the qubit state in a novel all-optical manner. We showed\r\nthat the microwave-optic transducer can be operated in a regime in which optical fields don’t\r\nharm the sensitive qubit. This is an important prerequisite for the operation of microwave-optic\r\ntransducers in conjunction with microwave quantum processors and brings the integration and\r\nseamless orchestration of different frequency components in a quantum network a step closer.\r\n","lang":"eng"}],"ddc":["530"],"department":[{"_id":"JoFi"},{"_id":"GradSch"}],"supervisor":[{"orcid":"0000-0001-8112-028X","last_name":"Fink","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","first_name":"Johannes M","full_name":"Fink, Johannes M"}],"page":"135","status":"public","date_published":"2025-01-24T00:00:00Z","title":"Microwave-optic interconnects for superconducting circuits","citation":{"short":"G.M. Arnold, Microwave-Optic Interconnects for Superconducting Circuits, Institute of Science and Technology Austria, 2025.","mla":"Arnold, Georg M. <i>Microwave-Optic Interconnects for Superconducting Circuits</i>. Institute of Science and Technology Austria, 2025, doi:<a href=\"https://doi.org/10.15479/at:ista:18871\">10.15479/at:ista:18871</a>.","chicago":"Arnold, Georg M. “Microwave-Optic Interconnects for Superconducting Circuits.” Institute of Science and Technology Austria, 2025. <a href=\"https://doi.org/10.15479/at:ista:18871\">https://doi.org/10.15479/at:ista:18871</a>.","ieee":"G. M. Arnold, “Microwave-optic interconnects for superconducting circuits,” Institute of Science and Technology Austria, 2025.","apa":"Arnold, G. M. (2025). <i>Microwave-optic interconnects for superconducting circuits</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:18871\">https://doi.org/10.15479/at:ista:18871</a>","ista":"Arnold GM. 2025. Microwave-optic interconnects for superconducting circuits. Institute of Science and Technology Austria.","ama":"Arnold GM. Microwave-optic interconnects for superconducting circuits. 2025. doi:<a href=\"https://doi.org/10.15479/at:ista:18871\">10.15479/at:ista:18871</a>"},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publisher":"Institute of Science and Technology Austria","author":[{"full_name":"Arnold, Georg M","first_name":"Georg M","orcid":"0000-0003-1397-7876","last_name":"Arnold","id":"3770C838-F248-11E8-B48F-1D18A9856A87"}],"doi":"10.15479/at:ista:18871","oa_version":"Published Version","OA_place":"publisher","publication_status":"published","oa":1,"file_date_updated":"2026-01-29T23:30:03Z","degree_awarded":"PhD","has_accepted_license":"1","acknowledgement":"This work was supported by the European Research Council under grant agreement no. 758053\r\n(ERC StG QUNNECT) and the European Union’s Horizon 2020 research, innovation program\r\nunder grant agreement no. 899354 (FETopen SuperQuLAN) and the Austrian Science Fund\r\n(FWF) through BeyondC (F7105). I want to acknowledge generous support from the Austrian\r\nAcademy of Sciences from a DOC [Doctoral program of the Austrian Academy of Sciences]\r\nfellowship (no. 25129).\r\n","month":"01","date_updated":"2026-04-16T12:20:43Z","date_created":"2025-01-24T10:28:39Z","year":"2025","acknowledged_ssus":[{"_id":"SSU"},{"_id":"M-Shop"},{"_id":"NanoFab"}],"corr_author":"1","related_material":{"record":[{"status":"public","relation":"part_of_dissertation","id":"6609"},{"id":"8529","relation":"part_of_dissertation","status":"public"},{"id":"18953","status":"public","relation":"part_of_dissertation"},{"id":"10924","relation":"part_of_dissertation","status":"public"},{"relation":"part_of_dissertation","status":"public","id":"9114"},{"id":"13200","status":"public","relation":"part_of_dissertation"}]},"tmp":{"short":"CC BY-NC-SA (4.0)","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png"},"file":[{"file_name":"tex for upload.zip","date_updated":"2026-01-29T23:30:03Z","file_id":"18946","creator":"cchlebak","embargo_to":"open_access","relation":"source_file","date_created":"2025-01-29T08:38:08Z","file_size":18856130,"checksum":"71872702e8f46c275eaea44efc4d304f","content_type":"application/x-zip-compressed","access_level":"closed"},{"embargo":"2026-01-29","file_name":"ISTThesisGA2022_final.pdf","date_updated":"2026-01-29T23:30:03Z","file_id":"18947","creator":"cchlebak","relation":"main_file","date_created":"2025-01-29T08:38:34Z","file_size":17344760,"checksum":"dfaa06591970f4bff163705802fad56d","content_type":"application/pdf","access_level":"open_access"}],"_id":"18871","language":[{"iso":"eng"}],"day":"24","ec_funded":1,"publication_identifier":{"issn":["2663-337X"]},"alternative_title":["ISTA Thesis"],"project":[{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits","grant_number":"899354","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A"},{"name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies","_id":"2671EB66-B435-11E9-9278-68D0E5697425"},{"name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","grant_number":"F07105"}],"article_processing_charge":"No"},{"publication_identifier":{"issn":["2663-337X"],"isbn":["978-3-99078-030-5"]},"ec_funded":1,"article_processing_charge":"No","project":[{"_id":"26336814-B435-11E9-9278-68D0E5697425","grant_number":"758053","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354"},{"name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits","grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f"}],"alternative_title":["ISTA Thesis"],"acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"SSU"},{"_id":"NanoFab"}],"date_created":"2023-05-05T11:08:50Z","year":"2023","day":"05","keyword":["quantum optics","electrooptics","quantum networks","quantum communication","transduction"],"_id":"12900","language":[{"iso":"eng"}],"tmp":{"short":"CC BY-NC-SA (4.0)","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png"},"file":[{"relation":"source_file","embargo_to":"open_access","file_size":36767177,"date_created":"2023-05-09T08:45:14Z","access_level":"closed","content_type":"application/x-zip-compressed","checksum":"8cbdab9c37ee55e591092a6f66b272c4","file_name":"thesis.zip","date_updated":"2023-06-06T22:30:03Z","creator":"rsahu","file_id":"12928"},{"date_updated":"2023-07-06T11:37:40Z","creator":"rsahu","file_id":"12929","file_name":"thesis_pdfa_final.pdf","access_level":"closed","content_type":"application/pdf","checksum":"439659ead46618147309be39d9dd5a8c","relation":"main_file","file_size":17501990,"date_created":"2023-05-09T08:51:17Z"}],"corr_author":"1","related_material":{"record":[{"id":"13175","status":"public","relation":"new_edition"},{"id":"10924","relation":"part_of_dissertation","status":"public"},{"id":"9114","relation":"part_of_dissertation","status":"public"}]},"has_accepted_license":"1","file_date_updated":"2023-07-06T11:37:40Z","degree_awarded":"PhD","publication_status":"published","date_updated":"2026-04-15T06:43:26Z","month":"05","page":"190","supervisor":[{"first_name":"Johannes M","full_name":"Fink, Johannes M","orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink"}],"department":[{"_id":"GradSch"},{"_id":"JoFi"}],"ddc":["537","535","539"],"type":"dissertation","abstract":[{"lang":"eng","text":"About a 100 years ago, we discovered that our universe is inherently noisy, that is, measuring any physical quantity with a precision beyond a certain point is not possible because of an omnipresent inherent noise. We call this - the quantum noise. Certain physical processes allow this quantum noise to get correlated in conjugate physical variables. These quantum correlations can be used to go beyond the potential of our inherently noisy universe and obtain a quantum advantage over the classical applications. \r\n\r\nQuantum noise being inherent also means that, at the fundamental level, the physical quantities are not well defined and therefore, objects can stay in multiple states at the same time. For example, the position of a particle not being well defined means that the particle is in multiple positions at the same time. About 4 decades ago, we started exploring the possibility of using objects which can be in multiple states at the same time to increase the dimensionality in computation. Thus, the field of quantum computing was born. We discovered that using quantum entanglement, a property closely related to quantum correlations, can be used to speed up computation of certain problems, such as factorisation of large numbers, faster than any known classical algorithm. Thus began the pursuit to make quantum computers a reality. \r\n\r\nTill date, we have explored quantum control over many physical systems including photons, spins, atoms, ions and even simple circuits made up of superconducting material. However, there persists one ubiquitous theme. The more readily a system interacts with an external field or matter, the more easily we can control it. But this also means that such a system can easily interact with a noisy environment and quickly lose its coherence. Consequently, such systems like electron spins need to be protected from the environment to ensure the longevity of their coherence. Other systems like nuclear spins are naturally protected as they do not interact easily with the environment. But, due to the same reason, it is harder to interact with such systems. \r\n\r\nAfter decades of experimentation with various systems, we are convinced that no one type of quantum system would be the best for all the quantum applications. We would need hybrid systems which are all interconnected - much like the current internet where all sorts of devices can all talk to each other - but now for quantum devices. A quantum internet. \r\n\r\nOptical photons are the best contenders to carry information for the quantum internet. They can carry quantum information cheaply and without much loss - the same reasons which has made them the backbone of our current internet. Following this direction, many systems, like trapped ions, have already demonstrated successful quantum links over a large distances using optical photons. However, some of the most promising contenders for quantum computing which are based on microwave frequencies have been left behind. This is because high energy optical photons can adversely affect fragile low-energy microwave systems. \r\n\r\nIn this thesis, we present substantial progress on this missing quantum link between microwave and optics using electrooptical nonlinearities in lithium niobate. The nonlinearities are enhanced by using resonant cavities for all the involved modes leading to observation of strong direct coupling between optical and microwave frequencies. With this strong coupling we are not only able to achieve almost 100\\% internal conversion efficiency with low added noise, thus presenting a quantum-enabled transducer, but also we are able to observe novel effects such as cooling of a microwave mode using optics. The strong coupling regime also leads to direct observation of dynamical backaction effect between microwave and optical frequencies which are studied in detail here. Finally, we also report first observation of microwave-optics entanglement in form of two-mode squeezed vacuum squeezed 0.7dB below vacuum level. \r\nWith this new bridge between microwave and optics, the microwave-based quantum technologies can finally be a part of a quantum network which is based on optical photons - putting us one step closer to a future with quantum internet. "}],"oa_version":"Published Version","OA_place":"publisher","doi":"10.15479/at:ista:12900","author":[{"full_name":"Sahu, Rishabh","first_name":"Rishabh","orcid":"0000-0001-6264-2162","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","last_name":"Sahu"}],"user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","publisher":"Institute of Science and Technology Austria","citation":{"chicago":"Sahu, Rishabh. “Cavity Quantum Electrooptics.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:12900\">https://doi.org/10.15479/at:ista:12900</a>.","short":"R. Sahu, Cavity Quantum Electrooptics, Institute of Science and Technology Austria, 2023.","mla":"Sahu, Rishabh. <i>Cavity Quantum Electrooptics</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:12900\">10.15479/at:ista:12900</a>.","ama":"Sahu R. Cavity quantum electrooptics. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:12900\">10.15479/at:ista:12900</a>","apa":"Sahu, R. (2023). <i>Cavity quantum electrooptics</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:12900\">https://doi.org/10.15479/at:ista:12900</a>","ista":"Sahu R. 2023. Cavity quantum electrooptics. Institute of Science and Technology Austria.","ieee":"R. Sahu, “Cavity quantum electrooptics,” Institute of Science and Technology Austria, 2023."},"date_published":"2023-05-05T00:00:00Z","title":"Cavity quantum electrooptics","status":"public"},{"issue":"6646","scopus_import":"1","publication_identifier":{"eissn":["1095-9203"],"issn":["0036-8075"]},"ec_funded":1,"article_processing_charge":"No","project":[{"_id":"26336814-B435-11E9-9278-68D0E5697425","grant_number":"758053","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"grant_number":"754411","_id":"260C2330-B435-11E9-9278-68D0E5697425","name":"ISTplus - Postdoctoral Fellowships","call_identifier":"H2020"},{"call_identifier":"H2020","name":"Quantum readout techniques and technologies","grant_number":"862644","_id":"237CBA6C-32DE-11EA-91FC-C7463DDC885E"},{"_id":"2671EB66-B435-11E9-9278-68D0E5697425","name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies"},{"grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"}],"isi":1,"main_file_link":[{"url":"https://doi.org/10.48550/arXiv.2301.03315","open_access":"1"}],"date_created":"2023-05-31T11:39:24Z","year":"2023","keyword":["Multidisciplinary"],"day":"18","intvolume":"       380","_id":"13106","language":[{"iso":"eng"}],"corr_author":"1","related_material":{"record":[{"id":"13122","status":"public","relation":"research_data"}],"link":[{"url":"https://ista.ac.at/en/news/wiring-up-quantum-circuits-with-light/","description":"News on ISTA Website","relation":"press_release"}]},"acknowledgement":"This work was supported by the European Research Council (grant no. 758053, ERC StG QUNNECT) and the European Union’s Horizon 2020 Research and Innovation Program (grant no. 899354, FETopen SuperQuLAN). L.Q. acknowledges generous support from the ISTFELLOW program. W.H. is the recipient of an ISTplus postdoctoral fellowship with funding from the European Union’s Horizon 2020 Research and Innovation Program (Marie Sklodowska-Curie grant no. 754411). G.A. is the recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria. J.M.F. acknowledges support from the Austrian Science Fund (FWF) through BeyondC (grant no. F7105) and the European Union’s Horizon 2020 Research and Innovation Program (grant no. 862644, FETopen QUARTET).","oa":1,"publication_status":"published","date_updated":"2026-04-15T06:39:33Z","volume":380,"month":"05","quality_controlled":"1","arxiv":1,"publication":"Science","article_type":"original","page":"718-721","department":[{"_id":"JoFi"}],"type":"journal_article","abstract":[{"text":"Quantum entanglement is a key resource in currently developed quantum technologies. Sharing this fragile property between superconducting microwave circuits and optical or atomic systems would enable new functionalities, but this has been hindered by an energy scale mismatch of >104 and the resulting mutually imposed loss and noise. In this work, we created and verified entanglement between microwave and optical fields in a millikelvin environment. Using an optically pulsed superconducting electro-optical device, we show entanglement between propagating microwave and optical fields in the continuous variable domain. This achievement not only paves the way for entanglement between superconducting circuits and telecom wavelength light, but also has wide-ranging implications for hybrid quantum networks in the context of modularization, scaling, sensing, and cross-platform verification.","lang":"eng"}],"oa_version":"Preprint","doi":"10.1126/science.adg3812","pmid":1,"author":[{"first_name":"Rishabh","full_name":"Sahu, Rishabh","orcid":"0000-0001-6264-2162","last_name":"Sahu","id":"47D26E34-F248-11E8-B48F-1D18A9856A87"},{"full_name":"Qiu, Liu","first_name":"Liu","orcid":"0000-0003-4345-4267","last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac"},{"first_name":"William J","full_name":"Hease, William J","last_name":"Hease","id":"29705398-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-9868-2166"},{"orcid":"0000-0003-1397-7876","id":"3770C838-F248-11E8-B48F-1D18A9856A87","last_name":"Arnold","first_name":"Georg M","full_name":"Arnold, Georg M"},{"last_name":"Minoguchi","first_name":"Y.","full_name":"Minoguchi, Y."},{"first_name":"P.","full_name":"Rabl, P.","last_name":"Rabl"},{"full_name":"Fink, Johannes M","first_name":"Johannes M","last_name":"Fink","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-8112-028X"}],"publisher":"American Association for the Advancement of Science","citation":{"chicago":"Sahu, Rishabh, Liu Qiu, William J Hease, Georg M Arnold, Y. Minoguchi, P. Rabl, and Johannes M Fink. “Entangling Microwaves with Light.” <i>Science</i>. American Association for the Advancement of Science, 2023. <a href=\"https://doi.org/10.1126/science.adg3812\">https://doi.org/10.1126/science.adg3812</a>.","mla":"Sahu, Rishabh, et al. “Entangling Microwaves with Light.” <i>Science</i>, vol. 380, no. 6646, American Association for the Advancement of Science, 2023, pp. 718–21, doi:<a href=\"https://doi.org/10.1126/science.adg3812\">10.1126/science.adg3812</a>.","short":"R. Sahu, L. Qiu, W.J. Hease, G.M. Arnold, Y. Minoguchi, P. Rabl, J.M. Fink, Science 380 (2023) 718–721.","ama":"Sahu R, Qiu L, Hease WJ, et al. Entangling microwaves with light. <i>Science</i>. 2023;380(6646):718-721. doi:<a href=\"https://doi.org/10.1126/science.adg3812\">10.1126/science.adg3812</a>","ieee":"R. Sahu <i>et al.</i>, “Entangling microwaves with light,” <i>Science</i>, vol. 380, no. 6646. American Association for the Advancement of Science, pp. 718–721, 2023.","ista":"Sahu R, Qiu L, Hease WJ, Arnold GM, Minoguchi Y, Rabl P, Fink JM. 2023. Entangling microwaves with light. Science. 380(6646), 718–721.","apa":"Sahu, R., Qiu, L., Hease, W. J., Arnold, G. M., Minoguchi, Y., Rabl, P., &#38; Fink, J. M. (2023). Entangling microwaves with light. <i>Science</i>. American Association for the Advancement of Science. <a href=\"https://doi.org/10.1126/science.adg3812\">https://doi.org/10.1126/science.adg3812</a>"},"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","title":"Entangling microwaves with light","date_published":"2023-05-18T00:00:00Z","external_id":{"pmid":["37200415"],"isi":["000996515200004"],"arxiv":["2301.03315"]},"status":"public"},{"tmp":{"short":"CC BY-NC-SA (4.0)","name":"Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International (CC BY-NC-SA 4.0)","legal_code_url":"https://creativecommons.org/licenses/by-nc-sa/4.0/legalcode","image":"/images/cc_by_nc_sa.png"},"file":[{"checksum":"7d03f1a5a5258ee43dfc3323dea4e08f","content_type":"application/pdf","access_level":"open_access","relation":"main_file","file_size":18688376,"date_created":"2023-06-30T08:17:25Z","date_updated":"2023-06-30T08:17:25Z","file_id":"13176","success":1,"creator":"cchlebak","file_name":"thesis_pdfa.pdf"},{"relation":"source_file","file_size":37847025,"date_created":"2023-07-06T11:35:15Z","access_level":"closed","content_type":"application/x-zip-compressed","checksum":"c3b45317ae58e0527533f98c202d81b7","file_name":"thesis.zip","date_updated":"2023-07-06T11:35:15Z","creator":"cchlebak","file_id":"13196"}],"corr_author":"1","related_material":{"record":[{"relation":"old_edition","status":"public","id":"12900"},{"status":"public","relation":"part_of_dissertation","id":"10924"},{"id":"9114","status":"public","relation":"part_of_dissertation"}]},"day":"05","keyword":["quantum optics","electrooptics","quantum networks","quantum communication","transduction"],"_id":"13175","language":[{"iso":"eng"}],"date_created":"2023-06-30T08:07:43Z","year":"2023","acknowledged_ssus":[{"_id":"M-Shop"},{"_id":"SSU"},{"_id":"NanoFab"}],"article_processing_charge":"No","alternative_title":["ISTA Thesis"],"project":[{"name":"A Fiber Optic Transceiver for Superconducting Qubits","call_identifier":"H2020","_id":"26336814-B435-11E9-9278-68D0E5697425","grant_number":"758053"},{"grant_number":"899354","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"}],"publication_identifier":{"isbn":["978-3-99078-030-5"],"issn":["2663-337X"]},"ec_funded":1,"author":[{"last_name":"Sahu","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6264-2162","full_name":"Sahu, Rishabh","first_name":"Rishabh"}],"user_id":"ba8df636-2132-11f1-aed0-ed93e2281fdd","citation":{"chicago":"Sahu, Rishabh. “Cavity Quantum Electrooptics.” Institute of Science and Technology Austria, 2023. <a href=\"https://doi.org/10.15479/at:ista:13175\">https://doi.org/10.15479/at:ista:13175</a>.","short":"R. Sahu, Cavity Quantum Electrooptics, Institute of Science and Technology Austria, 2023.","mla":"Sahu, Rishabh. <i>Cavity Quantum Electrooptics</i>. Institute of Science and Technology Austria, 2023, doi:<a href=\"https://doi.org/10.15479/at:ista:13175\">10.15479/at:ista:13175</a>.","ama":"Sahu R. Cavity quantum electrooptics. 2023. doi:<a href=\"https://doi.org/10.15479/at:ista:13175\">10.15479/at:ista:13175</a>","ieee":"R. Sahu, “Cavity quantum electrooptics,” Institute of Science and Technology Austria, 2023.","ista":"Sahu R. 2023. Cavity quantum electrooptics. Institute of Science and Technology Austria.","apa":"Sahu, R. (2023). <i>Cavity quantum electrooptics</i>. Institute of Science and Technology Austria. <a href=\"https://doi.org/10.15479/at:ista:13175\">https://doi.org/10.15479/at:ista:13175</a>"},"publisher":"Institute of Science and Technology Austria","OA_place":"publisher","oa_version":"Published Version","doi":"10.15479/at:ista:13175","status":"public","date_published":"2023-05-05T00:00:00Z","title":"Cavity quantum electrooptics","supervisor":[{"orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink","full_name":"Fink, Johannes M","first_name":"Johannes M"}],"page":"202","ddc":["537","535","539"],"department":[{"_id":"GradSch"},{"_id":"JoFi"}],"abstract":[{"text":"About a 100 years ago, we discovered that our universe is inherently noisy, that is, measuring any physical quantity with a precision beyond a certain point is not possible because of an omnipresent inherent noise. We call this - the quantum noise. Certain physical processes allow this quantum noise to get correlated in conjugate physical variables. These quantum correlations can be used to go beyond the potential of our inherently noisy universe and obtain a quantum advantage over the classical applications. \r\n\r\nQuantum noise being inherent also means that, at the fundamental level, the physical quantities are not well defined and therefore, objects can stay in multiple states at the same time. For example, the position of a particle not being well defined means that the particle is in multiple positions at the same time. About 4 decades ago, we started exploring the possibility of using objects which can be in multiple states at the same time to increase the dimensionality in computation. Thus, the field of quantum computing was born. We discovered that using quantum entanglement, a property closely related to quantum correlations, can be used to speed up computation of certain problems, such as factorisation of large numbers, faster than any known classical algorithm. Thus began the pursuit to make quantum computers a reality. \r\n\r\nTill date, we have explored quantum control over many physical systems including photons, spins, atoms, ions and even simple circuits made up of superconducting material. However, there persists one ubiquitous theme. The more readily a system interacts with an external field or matter, the more easily we can control it. But this also means that such a system can easily interact with a noisy environment and quickly lose its coherence. Consequently, such systems like electron spins need to be protected from the environment to ensure the longevity of their coherence. Other systems like nuclear spins are naturally protected as they do not interact easily with the environment. But, due to the same reason, it is harder to interact with such systems. \r\n\r\nAfter decades of experimentation with various systems, we are convinced that no one type of quantum system would be the best for all the quantum applications. We would need hybrid systems which are all interconnected - much like the current internet where all sorts of devices can all talk to each other - but now for quantum devices. A quantum internet. \r\n\r\nOptical photons are the best contenders to carry information for the quantum internet. They can carry quantum information cheaply and without much loss - the same reasons which has made them the backbone of our current internet. Following this direction, many systems, like trapped ions, have already demonstrated successful quantum links over a large distances using optical photons. However, some of the most promising contenders for quantum computing which are based on microwave frequencies have been left behind. This is because high energy optical photons can adversely affect fragile low-energy microwave systems. \r\n\r\nIn this thesis, we present substantial progress on this missing quantum link between microwave and optics using electrooptical nonlinearities in lithium niobate. The nonlinearities are enhanced by using resonant cavities for all the involved modes leading to observation of strong direct coupling between optical and microwave frequencies. With this strong coupling we are not only able to achieve almost 100\\% internal conversion efficiency with low added noise, thus presenting a quantum-enabled transducer, but also we are able to observe novel effects such as cooling of a microwave mode using optics. The strong coupling regime also leads to direct observation of dynamical backaction effect between microwave and optical frequencies which are studied in detail here. Finally, we also report first observation of microwave-optics entanglement in form of two-mode squeezed vacuum squeezed 0.7dB below vacuum level. \r\nWith this new bridge between microwave and optics, the microwave-based quantum technologies can finally be a part of a quantum network which is based on optical photons - putting us one step closer to a future with quantum internet. ","lang":"eng"}],"type":"dissertation","date_updated":"2026-04-15T06:43:26Z","month":"05","has_accepted_license":"1","publication_status":"published","degree_awarded":"PhD","file_date_updated":"2023-07-06T11:35:15Z","oa":1},{"date_created":"2023-07-09T22:01:11Z","year":"2023","isi":1,"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"file":[{"file_name":"2023_NatureComms_Qiu.pdf","date_updated":"2023-07-10T10:10:54Z","creator":"alisjak","success":1,"file_id":"13206","relation":"main_file","date_created":"2023-07-10T10:10:54Z","file_size":1349134,"access_level":"open_access","content_type":"application/pdf","checksum":"ec7ccd2c08f90d59cab302fd0d7776a4"}],"corr_author":"1","related_material":{"record":[{"relation":"dissertation_contains","status":"public","id":"18871"}]},"day":"24","language":[{"iso":"eng"}],"_id":"13200","intvolume":"        14","ec_funded":1,"publication_identifier":{"eissn":["2041-1723"]},"scopus_import":"1","project":[{"_id":"26336814-B435-11E9-9278-68D0E5697425","grant_number":"758053","name":"A Fiber Optic Transceiver for Superconducting Qubits","call_identifier":"H2020"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","name":"Quantum Local Area Networks with Superconducting Qubits","call_identifier":"H2020"},{"_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","grant_number":"F07105","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"},{"grant_number":"754411","_id":"260C2330-B435-11E9-9278-68D0E5697425","name":"ISTplus - Postdoctoral Fellowships","call_identifier":"H2020"},{"name":"International IST Postdoc Fellowship Programme","call_identifier":"FP7","grant_number":"291734","_id":"25681D80-B435-11E9-9278-68D0E5697425"},{"_id":"2671EB66-B435-11E9-9278-68D0E5697425","name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies"},{"_id":"3AC91DDA-15DF-11EA-824D-93A3E7B544D1","name":"FWF Open Access Fund","call_identifier":"FWF"}],"APC_amount":"6228 EUR","article_processing_charge":"Yes","department":[{"_id":"JoFi"}],"ddc":["000"],"abstract":[{"text":"Recent quantum technologies have established precise quantum control of various microscopic systems using electromagnetic waves. Interfaces based on cryogenic cavity electro-optic systems are particularly promising, due to the direct interaction between microwave and optical fields in the quantum regime. Quantum optical control of superconducting microwave circuits has been precluded so far due to the weak electro-optical coupling as well as quasi-particles induced by the pump laser. Here we report the coherent control of a superconducting microwave cavity using laser pulses in a multimode electro-optical device at millikelvin temperature with near-unity cooperativity. Both the stationary and instantaneous responses of the microwave and optical modes comply with the coherent electro-optical interaction, and reveal only minuscule amount of excess back-action with an unanticipated time delay. Our demonstration enables wide ranges of applications beyond quantum transductions, from squeezing and quantum non-demolition measurements of microwave fields, to entanglement generation and hybrid quantum networks.","lang":"eng"}],"type":"journal_article","article_type":"original","OA_type":"gold","status":"public","article_number":"3784","date_published":"2023-06-24T00:00:00Z","title":"Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action","external_id":{"arxiv":["2210.12443"],"pmid":["37355691"],"isi":["001018100800002"]},"author":[{"first_name":"Liu","full_name":"Qiu, Liu","orcid":"0000-0003-4345-4267","last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac"},{"orcid":"0000-0001-6264-2162","last_name":"Sahu","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","full_name":"Sahu, Rishabh","first_name":"Rishabh"},{"id":"29705398-F248-11E8-B48F-1D18A9856A87","last_name":"Hease","orcid":"0000-0001-9868-2166","full_name":"Hease, William J","first_name":"William J"},{"id":"3770C838-F248-11E8-B48F-1D18A9856A87","last_name":"Arnold","orcid":"0000-0003-1397-7876","full_name":"Arnold, Georg M","first_name":"Georg M"},{"id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink","orcid":"0000-0001-8112-028X","first_name":"Johannes M","full_name":"Fink, Johannes M"}],"publisher":"Nature Research","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","citation":{"ama":"Qiu L, Sahu R, Hease WJ, Arnold GM, Fink JM. Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action. <i>Nature Communications</i>. 2023;14. doi:<a href=\"https://doi.org/10.1038/s41467-023-39493-3\">10.1038/s41467-023-39493-3</a>","ista":"Qiu L, Sahu R, Hease WJ, Arnold GM, Fink JM. 2023. Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action. Nature Communications. 14, 3784.","apa":"Qiu, L., Sahu, R., Hease, W. J., Arnold, G. M., &#38; Fink, J. M. (2023). Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action. <i>Nature Communications</i>. Nature Research. <a href=\"https://doi.org/10.1038/s41467-023-39493-3\">https://doi.org/10.1038/s41467-023-39493-3</a>","ieee":"L. Qiu, R. Sahu, W. J. Hease, G. M. Arnold, and J. M. Fink, “Coherent optical control of a superconducting microwave cavity via electro-optical dynamical back-action,” <i>Nature Communications</i>, vol. 14. Nature Research, 2023.","chicago":"Qiu, Liu, Rishabh Sahu, William J Hease, Georg M Arnold, and Johannes M Fink. “Coherent Optical Control of a Superconducting Microwave Cavity via Electro-Optical Dynamical Back-Action.” <i>Nature Communications</i>. Nature Research, 2023. <a href=\"https://doi.org/10.1038/s41467-023-39493-3\">https://doi.org/10.1038/s41467-023-39493-3</a>.","short":"L. Qiu, R. Sahu, W.J. Hease, G.M. Arnold, J.M. Fink, Nature Communications 14 (2023).","mla":"Qiu, Liu, et al. “Coherent Optical Control of a Superconducting Microwave Cavity via Electro-Optical Dynamical Back-Action.” <i>Nature Communications</i>, vol. 14, 3784, Nature Research, 2023, doi:<a href=\"https://doi.org/10.1038/s41467-023-39493-3\">10.1038/s41467-023-39493-3</a>."},"OA_place":"publisher","oa_version":"Published Version","doi":"10.1038/s41467-023-39493-3","pmid":1,"publication_status":"published","file_date_updated":"2023-07-10T10:10:54Z","oa":1,"has_accepted_license":"1","acknowledgement":"This work was supported by the European Research Council under grant agreement no. 758053 (ERC StG QUNNECT), the European Union’s Horizon 2020 research and innovation program under grant agreement no. 899354 (FETopen SuperQuLAN), and the Austrian Science Fund (FWF) through BeyondC (F7105). L.Q. acknowledges generous support from the ISTFELLOW programme. W.H. is the recipient of an ISTplus postdoctoral fellowship with funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement no. 754411. G.A. is the recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria.","publication":"Nature Communications","month":"06","quality_controlled":"1","arxiv":1,"DOAJ_listed":"1","volume":14,"date_updated":"2026-08-21T22:30:34Z"},{"ec_funded":1,"project":[{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","name":"A Fiber Optic Transceiver for Superconducting Qubits","call_identifier":"H2020"},{"grant_number":"101089099","_id":"bdadfa0d-d553-11ed-ba76-fb85edbd456a","name":"Cavity Quantum Electro Optics: Microwave photonics with nonclassical states"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies","_id":"2671EB66-B435-11E9-9278-68D0E5697425"},{"grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"}],"article_processing_charge":"No","date_created":"2025-01-29T11:11:34Z","year":"2023","main_file_link":[{"url":"https://doi.org/10.48550/arXiv.2310.16817","open_access":"1"}],"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"corr_author":"1","related_material":{"record":[{"relation":"later_version","status":"public","id":"19073"},{"relation":"dissertation_contains","status":"public","id":"18871"}]},"day":"25","language":[{"iso":"eng"}],"_id":"18953","publication_status":"draft","oa":1,"acknowledgement":"We thank F. Hassani and M. Zemlicka for assistance\r\nwith qubit design and high power readout respectively,\r\nand P. Winkel and I. Pop at KIT for providing the JPA.\r\nThis work was supported by the European Research\r\nCouncil under grant agreement no. 758053 (ERC StG\r\nQUNNECT) and no. 101089099 (ERC CoG cQEO), the\r\nEuropean Union’s Horizon 2020 research and innovation\r\nprogram under grant agreement no. 899354 (FETopen\r\nSuperQuLAN) and the Austrian Science Fund (FWF)\r\nthrough BeyondC (grant no. F7105). L.Q. acknowledges\r\ngenerous support from the ISTFELLOW programme\r\nand G.A. is the recipient of a DOC fellowship of the\r\nAustrian Academy of Sciences at IST Austria.","publication":"arXiv","month":"10","arxiv":1,"date_updated":"2026-08-21T22:30:34Z","department":[{"_id":"JoFi"}],"abstract":[{"text":"The rapid development of superconducting quantum hardware is expected to run into significant I/O restrictions due to the need for large-scale error correction in a cryogenic environment. Classical data centers rely on fiber-optic interconnects to remove similar networking bottlenecks and to allow for reconfigurable, software-defined infrastructures. In the same spirit, ultra-cold electro-optic links have been proposed and used to generate qubit control signals, or to replace cryogenic readout electronics. So far, the latter suffered from either low efficiency, low bandwidth and the need for additional microwave drives, or breaking of Cooper pairs and qubit states. In this work we realize electro-optic microwave photonics at millikelvin temperatures to implement a radio-over-fiber qubit readout that does not require any active or passive cryogenic microwave equipment. We demonstrate all-optical single-shot-readout by means of the Jaynes-Cummings nonlinearity in a circulator-free readout scheme. Importantly, we do not observe any direct radiation impact on the qubit state as verified with high-fidelity quantum-non-demolition measurements despite the absence of shielding elements. This compatibility between superconducting circuits and telecom wavelength light is not only a prerequisite to establish modular quantum networks, it is also relevant for multiplexed readout of superconducting photon detectors and classical superconducting logic. Moreover, this experiment showcases the potential of electro-optic radiometry in harsh environments - an electronics-free sensing principle that extends into the THz regime with applications in radio astronomy, planetary missions and earth observation.","lang":"eng"}],"type":"preprint","status":"public","title":"All-optical single-shot readout of a superconducting qubit","date_published":"2023-10-25T00:00:00Z","external_id":{"arxiv":["2310.16817"]},"author":[{"first_name":"Georg M","full_name":"Arnold, Georg M","orcid":"0000-0003-1397-7876","last_name":"Arnold","id":"3770C838-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Werner","id":"1fcd8497-dba3-11ea-a45e-c6fbd715f7c7","orcid":"0009-0001-2346-5236","full_name":"Werner, Thomas","first_name":"Thomas"},{"first_name":"Rishabh","full_name":"Sahu, Rishabh","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","last_name":"Sahu","orcid":"0000-0001-6264-2162"},{"first_name":"Lucky","full_name":"Kapoor, Lucky","orcid":"0000-0001-8319-2148","id":"84b9700b-15b2-11ec-abd3-831089e67615","last_name":"Kapoor"},{"full_name":"Qiu, Liu","first_name":"Liu","orcid":"0000-0003-4345-4267","last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac"},{"id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink","orcid":"0000-0001-8112-028X","full_name":"Fink, Johannes M","first_name":"Johannes M"}],"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","citation":{"ista":"Arnold GM, Werner T, Sahu R, Kapoor L, Qiu L, Fink JM. All-optical single-shot readout of a superconducting qubit. arXiv, <a href=\"https://doi.org/10.48550/ARXIV.2310.16817\">10.48550/ARXIV.2310.16817</a>.","apa":"Arnold, G. M., Werner, T., Sahu, R., Kapoor, L., Qiu, L., &#38; Fink, J. M. (n.d.). All-optical single-shot readout of a superconducting qubit. <i>arXiv</i>. <a href=\"https://doi.org/10.48550/ARXIV.2310.16817\">https://doi.org/10.48550/ARXIV.2310.16817</a>","ieee":"G. M. Arnold, T. Werner, R. Sahu, L. Kapoor, L. Qiu, and J. M. Fink, “All-optical single-shot readout of a superconducting qubit,” <i>arXiv</i>. .","ama":"Arnold GM, Werner T, Sahu R, Kapoor L, Qiu L, Fink JM. All-optical single-shot readout of a superconducting qubit. <i>arXiv</i>. doi:<a href=\"https://doi.org/10.48550/ARXIV.2310.16817\">10.48550/ARXIV.2310.16817</a>","mla":"Arnold, Georg M., et al. “All-Optical Single-Shot Readout of a Superconducting Qubit.” <i>ArXiv</i>, doi:<a href=\"https://doi.org/10.48550/ARXIV.2310.16817\">10.48550/ARXIV.2310.16817</a>.","short":"G.M. Arnold, T. Werner, R. Sahu, L. Kapoor, L. Qiu, J.M. Fink, ArXiv (n.d.).","chicago":"Arnold, Georg M, Thomas Werner, Rishabh Sahu, Lucky Kapoor, Liu Qiu, and Johannes M Fink. “All-Optical Single-Shot Readout of a Superconducting Qubit.” <i>ArXiv</i>, n.d. <a href=\"https://doi.org/10.48550/ARXIV.2310.16817\">https://doi.org/10.48550/ARXIV.2310.16817</a>."},"oa_version":"Preprint","OA_place":"repository","doi":"10.48550/ARXIV.2310.16817"},{"acknowledgement":"We thank T. Mavrogordatos and D. Zhu for initial contribution on the presented topic and K. Fedorov for stimulating discussions on entangled microwave beams. This work was supported by the Austrian Science Fund (FWF) through Grant No. P32299 (PHONED) and the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 899354 (SuperQuLAN). Most of the computational results presented were obtained using the CLIP cluster [65].","oa":1,"publication_status":"published","date_updated":"2025-04-14T07:53:28Z","volume":105,"quality_controlled":"1","month":"06","arxiv":1,"publication":"Physical Review A","article_type":"original","department":[{"_id":"JoFi"}],"abstract":[{"text":"We investigate the deterministic generation and distribution of entanglement in large quantum networks by driving distant qubits with the output fields of a nondegenerate parametric amplifier. In this setting, the amplifier produces a continuous Gaussian two-mode squeezed state, which acts as a quantum-correlated reservoir for the qubits and relaxes them into a highly entangled steady state. Here we are interested in the maximal amount of entanglement and the optimal entanglement generation rates that can be achieved with this scheme under realistic conditions taking, in particular, the finite amplifier bandwidth, waveguide losses, and propagation delays into account. By combining exact numerical simulations of the full network with approximate analytic results, we predict the optimal working point for the amplifier and the corresponding qubit-qubit entanglement under various conditions. Our findings show that this passive conversion of Gaussian into discrete-variable entanglement offers a robust and experimentally very attractive approach for operating large optical, microwave, or hybrid quantum networks, for which efficient parametric amplifiers are currently developed.","lang":"eng"}],"type":"journal_article","oa_version":"Preprint","doi":"10.1103/PhysRevA.105.062454","author":[{"last_name":"Agustí","full_name":"Agustí, J.","first_name":"J."},{"last_name":"Minoguchi","first_name":"Y.","full_name":"Minoguchi, Y."},{"first_name":"Johannes M","full_name":"Fink, Johannes M","orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink"},{"full_name":"Rabl, P.","first_name":"P.","last_name":"Rabl"}],"citation":{"short":"J. Agustí, Y. Minoguchi, J.M. Fink, P. Rabl, Physical Review A 105 (2022).","mla":"Agustí, J., et al. “Long-Distance Distribution of Qubit-Qubit Entanglement Using Gaussian-Correlated Photonic Beams.” <i>Physical Review A</i>, vol. 105, no. 6, 062454, American Physical Society, 2022, doi:<a href=\"https://doi.org/10.1103/PhysRevA.105.062454\">10.1103/PhysRevA.105.062454</a>.","chicago":"Agustí, J., Y. Minoguchi, Johannes M Fink, and P. Rabl. “Long-Distance Distribution of Qubit-Qubit Entanglement Using Gaussian-Correlated Photonic Beams.” <i>Physical Review A</i>. American Physical Society, 2022. <a href=\"https://doi.org/10.1103/PhysRevA.105.062454\">https://doi.org/10.1103/PhysRevA.105.062454</a>.","ista":"Agustí J, Minoguchi Y, Fink JM, Rabl P. 2022. Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams. Physical Review A. 105(6), 062454.","apa":"Agustí, J., Minoguchi, Y., Fink, J. M., &#38; Rabl, P. (2022). Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams. <i>Physical Review A</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevA.105.062454\">https://doi.org/10.1103/PhysRevA.105.062454</a>","ieee":"J. Agustí, Y. Minoguchi, J. M. Fink, and P. Rabl, “Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams,” <i>Physical Review A</i>, vol. 105, no. 6. American Physical Society, 2022.","ama":"Agustí J, Minoguchi Y, Fink JM, Rabl P. Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams. <i>Physical Review A</i>. 2022;105(6). doi:<a href=\"https://doi.org/10.1103/PhysRevA.105.062454\">10.1103/PhysRevA.105.062454</a>"},"user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","publisher":"American Physical Society","date_published":"2022-06-29T00:00:00Z","article_number":"062454","title":"Long-distance distribution of qubit-qubit entanglement using Gaussian-correlated photonic beams","external_id":{"isi":["000824330200003"],"arxiv":["2204.02993"]},"status":"public","issue":"6","scopus_import":"1","publication_identifier":{"issn":["2469-9926"],"eissn":["2469-9934"]},"ec_funded":1,"article_processing_charge":"No","project":[{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","name":"Quantum Local Area Networks with Superconducting Qubits","call_identifier":"H2020"}],"isi":1,"main_file_link":[{"open_access":"1","url":" https://doi.org/10.48550/arXiv.2204.02993"}],"year":"2022","date_created":"2022-07-17T22:01:55Z","day":"29","language":[{"iso":"eng"}],"_id":"11591","intvolume":"       105"},{"publication_status":"published","oa":1,"file_date_updated":"2022-03-28T08:02:12Z","acknowledgement":"The authors thank S. Wald and F. Diorico for their help with optical filtering, O. Hosten\r\nand M. Aspelmeyer for equipment, H.G.L. Schwefel for materials and discussions, L.\r\nDrmic and P. Zielinski for software support, and the MIBA workshop at IST Austria for\r\nmachining the microwave cavity. This work was supported by the European Research\r\nCouncil under grant agreement no. 758053 (ERC StG QUNNECT) and the European\r\nUnion’s Horizon 2020 research and innovation program under grant agreement no.\r\n899354 (FETopen SuperQuLAN). W.H. is the recipient of an ISTplus postdoctoral fellowship\r\nwith funding from the European Union’s Horizon 2020 research and innovation\r\nprogram under the Marie Skłodowska-Curie grant agreement no. 754411. G.A. is the\r\nrecipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria. J.M.F.\r\nacknowledges support from the Austrian Science Fund (FWF) through BeyondC (F7105)\r\nand the European Union’s Horizon 2020 research and innovation programs under grant\r\nagreement no. 862644 (FETopen QUARTET).","has_accepted_license":"1","publication":"Nature Communications","arxiv":1,"quality_controlled":"1","month":"03","volume":13,"date_updated":"2026-08-21T22:30:34Z","type":"journal_article","abstract":[{"text":"Solid-state microwave systems offer strong interactions for fast quantum logic and sensing but photons at telecom wavelength are the ideal choice for high-density low-loss quantum interconnects. A general-purpose interface that can make use of single photon effects requires < 1 input noise quanta, which has remained elusive due to either low efficiency or pump induced heating. Here we demonstrate coherent electro-optic modulation on nanosecond-timescales with only 0.16+0.02−0.01 microwave input noise photons with a total bidirectional transduction efficiency of 8.7% (or up to 15% with 0.41+0.02−0.02), as required for near-term heralded quantum network protocols. The use of short and high-power optical pump pulses also enables near-unity cooperativity of the electro-optic interaction leading to an internal pure conversion efficiency of up to 99.5%. Together with the low mode occupancy this provides evidence for electro-optic laser cooling and vacuum amplification as predicted a decade ago.","lang":"eng"}],"department":[{"_id":"JoFi"}],"ddc":["530"],"article_type":"original","status":"public","external_id":{"arxiv":["2107.08303"],"isi":["000767892300013"],"pmid":["35277488"]},"date_published":"2022-03-11T00:00:00Z","title":"Quantum-enabled operation of a microwave-optical interface","article_number":"1276","citation":{"chicago":"Sahu, Rishabh, William J Hease, Alfredo R Rueda Sanchez, Georg M Arnold, Liu Qiu, and Johannes M Fink. “Quantum-Enabled Operation of a Microwave-Optical Interface.” <i>Nature Communications</i>. Springer Nature, 2022. <a href=\"https://doi.org/10.1038/s41467-022-28924-2\">https://doi.org/10.1038/s41467-022-28924-2</a>.","mla":"Sahu, Rishabh, et al. “Quantum-Enabled Operation of a Microwave-Optical Interface.” <i>Nature Communications</i>, vol. 13, 1276, Springer Nature, 2022, doi:<a href=\"https://doi.org/10.1038/s41467-022-28924-2\">10.1038/s41467-022-28924-2</a>.","short":"R. Sahu, W.J. Hease, A.R. Rueda Sanchez, G.M. Arnold, L. Qiu, J.M. Fink, Nature Communications 13 (2022).","ama":"Sahu R, Hease WJ, Rueda Sanchez AR, Arnold GM, Qiu L, Fink JM. Quantum-enabled operation of a microwave-optical interface. <i>Nature Communications</i>. 2022;13. doi:<a href=\"https://doi.org/10.1038/s41467-022-28924-2\">10.1038/s41467-022-28924-2</a>","ieee":"R. Sahu, W. J. Hease, A. R. Rueda Sanchez, G. M. Arnold, L. Qiu, and J. M. Fink, “Quantum-enabled operation of a microwave-optical interface,” <i>Nature Communications</i>, vol. 13. Springer Nature, 2022.","ista":"Sahu R, Hease WJ, Rueda Sanchez AR, Arnold GM, Qiu L, Fink JM. 2022. Quantum-enabled operation of a microwave-optical interface. Nature Communications. 13, 1276.","apa":"Sahu, R., Hease, W. J., Rueda Sanchez, A. R., Arnold, G. M., Qiu, L., &#38; Fink, J. M. (2022). Quantum-enabled operation of a microwave-optical interface. <i>Nature Communications</i>. Springer Nature. <a href=\"https://doi.org/10.1038/s41467-022-28924-2\">https://doi.org/10.1038/s41467-022-28924-2</a>"},"publisher":"Springer Nature","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"id":"47D26E34-F248-11E8-B48F-1D18A9856A87","last_name":"Sahu","orcid":"0000-0001-6264-2162","full_name":"Sahu, Rishabh","first_name":"Rishabh"},{"id":"29705398-F248-11E8-B48F-1D18A9856A87","last_name":"Hease","orcid":"0000-0001-9868-2166","first_name":"William J","full_name":"Hease, William J"},{"orcid":"0000-0001-6249-5860","last_name":"Rueda Sanchez","id":"3B82B0F8-F248-11E8-B48F-1D18A9856A87","first_name":"Alfredo R","full_name":"Rueda Sanchez, Alfredo R"},{"orcid":"0000-0003-1397-7876","id":"3770C838-F248-11E8-B48F-1D18A9856A87","last_name":"Arnold","full_name":"Arnold, Georg M","first_name":"Georg M"},{"last_name":"Qiu","id":"45e99c0d-1eb1-11eb-9b96-ed8ab2983cac","orcid":"0000-0003-4345-4267","first_name":"Liu","full_name":"Qiu, Liu"},{"first_name":"Johannes M","full_name":"Fink, Johannes M","orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87","last_name":"Fink"}],"pmid":1,"doi":"10.1038/s41467-022-28924-2","oa_version":"Published Version","ec_funded":1,"publication_identifier":{"eissn":["2041-1723"]},"scopus_import":"1","project":[{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"A Fiber Optic Transceiver for Superconducting Qubits"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"_id":"260C2330-B435-11E9-9278-68D0E5697425","grant_number":"754411","call_identifier":"H2020","name":"ISTplus - Postdoctoral Fellowships"},{"name":"Quantum readout techniques and technologies","call_identifier":"H2020","grant_number":"862644","_id":"237CBA6C-32DE-11EA-91FC-C7463DDC885E"},{"_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f","grant_number":"F07105","name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits"}],"article_processing_charge":"No","year":"2022","date_created":"2022-03-27T22:01:45Z","acknowledged_ssus":[{"_id":"M-Shop"}],"isi":1,"corr_author":"1","related_material":{"record":[{"id":"13175","status":"public","relation":"dissertation_contains"},{"id":"12900","relation":"dissertation_contains","status":"public"},{"id":"18871","relation":"dissertation_contains","status":"public"}]},"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"file":[{"date_created":"2022-03-28T08:02:12Z","file_size":1167492,"relation":"main_file","access_level":"open_access","checksum":"7c5176db7b8e2ed18a4e0c5aca70a72c","content_type":"application/pdf","file_name":"2022_NatureCommunications_Sahu.pdf","success":1,"creator":"dernst","file_id":"10929","date_updated":"2022-03-28T08:02:12Z"}],"_id":"10924","intvolume":"        13","language":[{"iso":"eng"}],"day":"11"},{"citation":{"ama":"Hease WJ, Rueda Sanchez AR, Sahu R, et al. Bidirectional electro-optic wavelength conversion in the quantum ground state. <i>PRX Quantum</i>. 2020;1(2). doi:<a href=\"https://doi.org/10.1103/prxquantum.1.020315\">10.1103/prxquantum.1.020315</a>","apa":"Hease, W. J., Rueda Sanchez, A. R., Sahu, R., Wulf, M., Arnold, G. M., Schwefel, H. G. L., &#38; Fink, J. M. (2020). Bidirectional electro-optic wavelength conversion in the quantum ground state. <i>PRX Quantum</i>. American Physical Society. <a href=\"https://doi.org/10.1103/prxquantum.1.020315\">https://doi.org/10.1103/prxquantum.1.020315</a>","ista":"Hease WJ, Rueda Sanchez AR, Sahu R, Wulf M, Arnold GM, Schwefel HGL, Fink JM. 2020. Bidirectional electro-optic wavelength conversion in the quantum ground state. PRX Quantum. 1(2), 020315.","ieee":"W. J. Hease <i>et al.</i>, “Bidirectional electro-optic wavelength conversion in the quantum ground state,” <i>PRX Quantum</i>, vol. 1, no. 2. American Physical Society, 2020.","chicago":"Hease, William J, Alfredo R Rueda Sanchez, Rishabh Sahu, Matthias Wulf, Georg M Arnold, Harald G.L. Schwefel, and Johannes M Fink. “Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State.” <i>PRX Quantum</i>. American Physical Society, 2020. <a href=\"https://doi.org/10.1103/prxquantum.1.020315\">https://doi.org/10.1103/prxquantum.1.020315</a>.","mla":"Hease, William J., et al. “Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State.” <i>PRX Quantum</i>, vol. 1, no. 2, 020315, American Physical Society, 2020, doi:<a href=\"https://doi.org/10.1103/prxquantum.1.020315\">10.1103/prxquantum.1.020315</a>.","short":"W.J. Hease, A.R. Rueda Sanchez, R. Sahu, M. Wulf, G.M. Arnold, H.G.L. Schwefel, J.M. Fink, PRX Quantum 1 (2020)."},"publisher":"American Physical Society","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","author":[{"orcid":"0000-0001-9868-2166","last_name":"Hease","id":"29705398-F248-11E8-B48F-1D18A9856A87","first_name":"William J","full_name":"Hease, William J"},{"first_name":"Alfredo R","full_name":"Rueda Sanchez, Alfredo R","id":"3B82B0F8-F248-11E8-B48F-1D18A9856A87","last_name":"Rueda Sanchez","orcid":"0000-0001-6249-5860"},{"last_name":"Sahu","id":"47D26E34-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6264-2162","first_name":"Rishabh","full_name":"Sahu, Rishabh"},{"first_name":"Matthias","full_name":"Wulf, Matthias","last_name":"Wulf","id":"45598606-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6613-1378"},{"full_name":"Arnold, Georg M","first_name":"Georg M","orcid":"0000-0003-1397-7876","last_name":"Arnold","id":"3770C838-F248-11E8-B48F-1D18A9856A87"},{"last_name":"Schwefel","first_name":"Harald G.L.","full_name":"Schwefel, Harald G.L."},{"first_name":"Johannes M","full_name":"Fink, Johannes M","orcid":"0000-0001-8112-028X","last_name":"Fink","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87"}],"doi":"10.1103/prxquantum.1.020315","oa_version":"Published Version","status":"public","external_id":{"isi":["000674680100001"]},"title":"Bidirectional electro-optic wavelength conversion in the quantum ground state","date_published":"2020-11-23T00:00:00Z","article_number":"020315","article_type":"original","type":"journal_article","abstract":[{"lang":"eng","text":"Microwave photonics lends the advantages of fiber optics to electronic sensing and communication systems. In contrast to nonlinear optics, electro-optic devices so far require classical modulation fields whose variance is dominated by electronic or thermal noise rather than quantum fluctuations. Here we demonstrate bidirectional single-sideband conversion of X band microwave to C band telecom light with a microwave mode occupancy as low as 0.025 ± 0.005 and an added output noise of less than or equal to 0.074 photons. This is facilitated by radiative cooling and a triply resonant ultra-low-loss transducer operating at millikelvin temperatures. The high bandwidth of 10.7 MHz and total (internal) photon conversion\r\nefficiency of 0.03% (0.67%) combined with the extremely slow heating rate of 1.1 added output noise photons per second for the highest available pump power of 1.48 mW puts near-unity efficiency pulsed quantum transduction within reach. Together with the non-Gaussian resources of superconducting qubits this might provide the practical foundation to extend the range and scope of current quantum networks in analogy to electrical repeaters in classical fiber optic communication."}],"department":[{"_id":"JoFi"}],"ddc":["530"],"volume":1,"date_updated":"2026-08-21T22:30:34Z","publication":"PRX Quantum","quality_controlled":"1","month":"11","acknowledgement":"The authors acknowledge the support of T. Menner, A. Arslani, and T. Asenov from the Miba machine shop for machining the microwave cavity, and thank S. Barzanjeh, F. Sedlmeir, and C. Marquardt for fruitful discussions. This work is supported by IST Austria and the European Research Council under Grant No. 758053 (ERC StG QUNNECT). W.H. is the recipient of an ISTplus postdoctoral fellowship with funding from the European Union’s Horizon 2020 research and innovation program under the Marie Skłodowska-Curie Grant No. 754411.\r\nG.A. is the recipient of a DOC fellowship of the Austrian Academy of Sciences at IST Austria. J.M.F. acknowledges support from the Austrian Science Fund (FWF) through BeyondC (F71) and the European Union’s Horizon 2020 research and innovation program under Grant No. 899354 (FET Open SuperQuLAN). H.G.L.S. acknowledges support from the Aotearoa/New Zealand’s MBIE Endeavour Smart Ideas Grant No UOOX1805.","has_accepted_license":"1","publication_status":"published","oa":1,"file_date_updated":"2021-02-12T11:16:16Z","corr_author":"1","related_material":{"record":[{"status":"public","relation":"research_data","id":"13071"},{"id":"13175","relation":"dissertation_contains","status":"public"},{"id":"12900","status":"public","relation":"dissertation_contains"},{"relation":"dissertation_contains","status":"public","id":"18871"}],"link":[{"url":"https://ist.ac.at/en/news/how-to-transport-microwave-quantum-information-via-optical-fiber/","relation":"press_release","description":"News on IST Homepage"}]},"file":[{"access_level":"open_access","checksum":"b70b12ded6d7660d4c9037eb09bfed0c","content_type":"application/pdf","relation":"main_file","file_size":2146924,"date_created":"2021-02-12T11:16:16Z","date_updated":"2021-02-12T11:16:16Z","creator":"dernst","success":1,"file_id":"9115","file_name":"2020_PRXQuantum_Hease.pdf"}],"tmp":{"short":"CC BY (4.0)","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","image":"/images/cc_by.png"},"_id":"9114","intvolume":"         1","language":[{"iso":"eng"}],"day":"23","isi":1,"year":"2020","date_created":"2021-02-12T10:41:28Z","acknowledged_ssus":[{"_id":"M-Shop"}],"article_processing_charge":"No","project":[{"name":"A Fiber Optic Transceiver for Superconducting Qubits","call_identifier":"H2020","grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425"},{"call_identifier":"H2020","name":"ISTplus - Postdoctoral Fellowships","_id":"260C2330-B435-11E9-9278-68D0E5697425","grant_number":"754411"},{"_id":"9B868D20-BA93-11EA-9121-9846C619BF3A","grant_number":"899354","call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits"},{"_id":"2671EB66-B435-11E9-9278-68D0E5697425","name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies"},{"name":"QUANTUM INFORMATION SYSTEMS BEYOND CLASSICAL CAPABILITIES / P5- Integration of Superconducting Quantum Circuits","grant_number":"F07105","_id":"bdb108fd-d553-11ed-ba76-83dc74a9864f"}],"publication_identifier":{"issn":["2691-3399"]},"scopus_import":"1","issue":"2","ec_funded":1}]