[{"year":"2022","acknowledgement":"We thank Marco Cerezo, Zoe Holmes, and Nicholas Hunter-Jones for fruitful discussion and valuable feedback. We also acknowledge Adam Smith, Johannes Jakob Meyer, and Victor V. Albert for comments on the paper. The simulations were performed in the Julia programming\r\nlanguage [65] using the Yao module [66]. S.H.S., R.A.M., A.A.M. and M.S. acknowledge support by the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 850899).","publisher":"American Physical Society","department":[{"_id":"MaSe"}],"publication_status":"published","related_material":{"record":[{"relation":"dissertation_contains","status":"public","id":"14622"}]},"author":[{"full_name":"Sack, Stefan","orcid":"0000-0001-5400-8508","id":"dd622248-f6e0-11ea-865d-ce382a1c81a5","last_name":"Sack","first_name":"Stefan"},{"id":"CE680B90-D85A-11E9-B684-C920E6697425","orcid":"0000-0002-5383-2869","first_name":"Raimel A","last_name":"Medina Ramos","full_name":"Medina Ramos, Raimel A"},{"orcid":"0000-0002-8443-1064","id":"36EBAD38-F248-11E8-B48F-1D18A9856A87","last_name":"Michailidis","first_name":"Alexios","full_name":"Michailidis, Alexios"},{"full_name":"Kueng, Richard","last_name":"Kueng","first_name":"Richard"},{"full_name":"Serbyn, Maksym","orcid":"0000-0002-2399-5827","id":"47809E7E-F248-11E8-B48F-1D18A9856A87","last_name":"Serbyn","first_name":"Maksym"}],"volume":3,"date_updated":"2023-12-13T14:47:24Z","date_created":"2022-06-29T20:21:32Z","article_number":"020365","ec_funded":1,"file_date_updated":"2022-06-30T07:14:48Z","oa":1,"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"external_id":{"arxiv":["2201.08194"],"isi":["000822564300001"]},"project":[{"grant_number":"850899","_id":"23841C26-32DE-11EA-91FC-C7463DDC885E","call_identifier":"H2020","name":"Non-Ergodic Quantum Matter: Universality, Dynamics and Control"}],"quality_controlled":"1","isi":1,"doi":"10.1103/prxquantum.3.020365","language":[{"iso":"eng"}],"publication_identifier":{"issn":["2691-3399"]},"month":"06","_id":"11471","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","intvolume":" 3","status":"public","ddc":["530"],"title":"Avoiding barren plateaus using classical shadows","file":[{"relation":"main_file","file_id":"11472","checksum":"a7706b28d24a0e32a55ea04b82a2df43","success":1,"date_created":"2022-06-30T07:14:48Z","date_updated":"2022-06-30T07:14:48Z","access_level":"open_access","file_name":"2022_PRXQuantum_Sack.pdf","content_type":"application/pdf","file_size":4231591,"creator":"dernst"}],"oa_version":"Published Version","type":"journal_article","issue":"2","abstract":[{"text":"Variational quantum algorithms are promising algorithms for achieving quantum advantage on nearterm devices. The quantum hardware is used to implement a variational wave function and measure observables, whereas the classical computer is used to store and update the variational parameters. The optimization landscape of expressive variational ansätze is however dominated by large regions in parameter space, known as barren plateaus, with vanishing gradients, which prevents efficient optimization. In this work we propose a general algorithm to avoid barren plateaus in the initialization and throughout the optimization. To this end we define a notion of weak barren plateaus (WBPs) based on the entropies of local reduced density matrices. The presence of WBPs can be efficiently quantified using recently introduced shadow tomography of the quantum state with a classical computer. We demonstrate that avoidance of WBPs suffices to ensure sizable gradients in the initialization. In addition, we demonstrate that decreasing the gradient step size, guided by the entropies allows WBPs to be avoided during the optimization process. This paves the way for efficient barren plateau-free optimization on near-term devices. ","lang":"eng"}],"citation":{"ista":"Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. 2022. Avoiding barren plateaus using classical shadows. PRX Quantum. 3(2), 020365.","ieee":"S. Sack, R. A. Medina Ramos, A. Michailidis, R. Kueng, and M. Serbyn, “Avoiding barren plateaus using classical shadows,” PRX Quantum, vol. 3, no. 2. American Physical Society, 2022.","apa":"Sack, S., Medina Ramos, R. A., Michailidis, A., Kueng, R., & Serbyn, M. (2022). Avoiding barren plateaus using classical shadows. PRX Quantum. American Physical Society. https://doi.org/10.1103/prxquantum.3.020365","ama":"Sack S, Medina Ramos RA, Michailidis A, Kueng R, Serbyn M. Avoiding barren plateaus using classical shadows. PRX Quantum. 2022;3(2). doi:10.1103/prxquantum.3.020365","chicago":"Sack, Stefan, Raimel A Medina Ramos, Alexios Michailidis, Richard Kueng, and Maksym Serbyn. “Avoiding Barren Plateaus Using Classical Shadows.” PRX Quantum. American Physical Society, 2022. https://doi.org/10.1103/prxquantum.3.020365.","mla":"Sack, Stefan, et al. “Avoiding Barren Plateaus Using Classical Shadows.” PRX Quantum, vol. 3, no. 2, 020365, American Physical Society, 2022, doi:10.1103/prxquantum.3.020365.","short":"S. Sack, R.A. Medina Ramos, A. Michailidis, R. Kueng, M. Serbyn, PRX Quantum 3 (2022)."},"publication":"PRX Quantum","article_type":"original","date_published":"2022-06-29T00:00:00Z","keyword":["General Medicine"],"article_processing_charge":"No","has_accepted_license":"1","day":"29"},{"publication_identifier":{"issn":["2691-3399"]},"month":"11","doi":"10.1103/prxquantum.1.020315","language":[{"iso":"eng"}],"acknowledged_ssus":[{"_id":"M-Shop"}],"tmp":{"name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","short":"CC BY (4.0)","image":"/images/cc_by.png"},"external_id":{"isi":["000674680100001"]},"oa":1,"project":[{"grant_number":"758053","_id":"26336814-B435-11E9-9278-68D0E5697425","name":"A Fiber Optic Transceiver for Superconducting Qubits","call_identifier":"H2020"},{"grant_number":"754411","_id":"260C2330-B435-11E9-9278-68D0E5697425","call_identifier":"H2020","name":"ISTplus - Postdoctoral Fellowships"},{"call_identifier":"H2020","name":"Quantum Local Area Networks with Superconducting Qubits","grant_number":"899354","_id":"9B868D20-BA93-11EA-9121-9846C619BF3A"},{"_id":"26927A52-B435-11E9-9278-68D0E5697425","grant_number":"F07105","name":"Integrating superconducting quantum circuits","call_identifier":"FWF"},{"_id":"2671EB66-B435-11E9-9278-68D0E5697425","name":"Coherent on-chip conversion of superconducting qubit signals from microwaves to optical frequencies"}],"isi":1,"quality_controlled":"1","ec_funded":1,"file_date_updated":"2021-02-12T11:16:16Z","article_number":"020315","related_material":{"link":[{"url":"https://ist.ac.at/en/news/how-to-transport-microwave-quantum-information-via-optical-fiber/","description":"News on IST Homepage","relation":"press_release"}],"record":[{"id":"13071","relation":"research_data","status":"public"},{"status":"public","relation":"dissertation_contains","id":"12900"},{"relation":"dissertation_contains","status":"public","id":"13175"}]},"author":[{"orcid":"0000-0001-9868-2166","id":"29705398-F248-11E8-B48F-1D18A9856A87","last_name":"Hease","first_name":"William J","full_name":"Hease, William J"},{"full_name":"Rueda Sanchez, Alfredo R","last_name":"Rueda Sanchez","first_name":"Alfredo R","orcid":"0000-0001-6249-5860","id":"3B82B0F8-F248-11E8-B48F-1D18A9856A87"},{"id":"47D26E34-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6264-2162","first_name":"Rishabh","last_name":"Sahu","full_name":"Sahu, Rishabh"},{"id":"45598606-F248-11E8-B48F-1D18A9856A87","orcid":"0000-0001-6613-1378","first_name":"Matthias","last_name":"Wulf","full_name":"Wulf, Matthias"},{"last_name":"Arnold","first_name":"Georg M","orcid":"0000-0003-1397-7876","id":"3770C838-F248-11E8-B48F-1D18A9856A87","full_name":"Arnold, Georg M"},{"full_name":"Schwefel, Harald G.L.","last_name":"Schwefel","first_name":"Harald G.L."},{"full_name":"Fink, Johannes M","last_name":"Fink","first_name":"Johannes M","orcid":"0000-0001-8112-028X","id":"4B591CBA-F248-11E8-B48F-1D18A9856A87"}],"volume":1,"date_updated":"2023-08-24T11:16:36Z","date_created":"2021-02-12T10:41:28Z","year":"2020","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.","department":[{"_id":"JoFi"}],"publisher":"American Physical Society","publication_status":"published","has_accepted_license":"1","article_processing_charge":"No","day":"23","date_published":"2020-11-23T00:00:00Z","citation":{"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).","mla":"Hease, William J., et al. “Bidirectional Electro-Optic Wavelength Conversion in the Quantum Ground State.” PRX Quantum, vol. 1, no. 2, 020315, American Physical Society, 2020, doi:10.1103/prxquantum.1.020315.","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.” PRX Quantum. American Physical Society, 2020. https://doi.org/10.1103/prxquantum.1.020315.","ama":"Hease WJ, Rueda Sanchez AR, Sahu R, et al. Bidirectional electro-optic wavelength conversion in the quantum ground state. PRX Quantum. 2020;1(2). doi:10.1103/prxquantum.1.020315","ieee":"W. J. Hease et al., “Bidirectional electro-optic wavelength conversion in the quantum ground state,” PRX Quantum, vol. 1, no. 2. American Physical Society, 2020.","apa":"Hease, W. J., Rueda Sanchez, A. R., Sahu, R., Wulf, M., Arnold, G. M., Schwefel, H. G. L., & Fink, J. M. (2020). Bidirectional electro-optic wavelength conversion in the quantum ground state. PRX Quantum. American Physical Society. https://doi.org/10.1103/prxquantum.1.020315","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."},"publication":"PRX Quantum","article_type":"original","issue":"2","abstract":[{"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.","lang":"eng"}],"type":"journal_article","file":[{"date_created":"2021-02-12T11:16:16Z","date_updated":"2021-02-12T11:16:16Z","checksum":"b70b12ded6d7660d4c9037eb09bfed0c","success":1,"relation":"main_file","file_id":"9115","content_type":"application/pdf","file_size":2146924,"creator":"dernst","file_name":"2020_PRXQuantum_Hease.pdf","access_level":"open_access"}],"oa_version":"Published Version","user_id":"4359f0d1-fa6c-11eb-b949-802e58b17ae8","_id":"9114","intvolume":" 1","status":"public","title":"Bidirectional electro-optic wavelength conversion in the quantum ground state","ddc":["530"]}]