{"author":[{"full_name":"Kun, Daniel","last_name":"Kun","first_name":"Daniel"},{"first_name":"Karl T","last_name":"Strömberg","id":"68011cd2-da32-11ee-a930-b2774c7aba5f","full_name":"Strömberg, Karl T"},{"last_name":"Spagnolo","first_name":"Michele","full_name":"Spagnolo, Michele"},{"last_name":"Dakić","first_name":"Borivoje","full_name":"Dakić, Borivoje"},{"full_name":"Rozema, Lee A.","last_name":"Rozema","first_name":"Lee A."},{"full_name":"Walther, Philip","last_name":"Walther","first_name":"Philip"}],"intvolume":"       111","article_number":"L050402","user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","quality_controlled":"1","language":[{"iso":"eng"}],"day":"16","OA_place":"publisher","publication_identifier":{"eissn":["2469-9934"],"issn":["2469-9926"]},"has_accepted_license":"1","article_type":"letter_note","date_updated":"2025-05-28T09:18:13Z","department":[{"_id":"OnHo"}],"doi":"10.1103/PhysRevA.111.L050402","publication_status":"published","oa_version":"Published Version","publication":"Physical Review A","_id":"19733","oa":1,"arxiv":1,"file":[{"file_name":"2025_PhysReviewA_Kun.pdf","relation":"main_file","success":1,"file_id":"19755","content_type":"application/pdf","file_size":571784,"checksum":"b83295a8f597b7781d8e7bfa3b393b42","date_created":"2025-05-28T09:16:03Z","access_level":"open_access","date_updated":"2025-05-28T09:16:03Z","creator":"dernst"}],"year":"2025","status":"public","tmp":{"image":"/images/cc_by.png","legal_code_url":"https://creativecommons.org/licenses/by/4.0/legalcode","name":"Creative Commons Attribution 4.0 International Public License (CC-BY 4.0)","short":"CC BY (4.0)"},"ddc":["530"],"abstract":[{"text":"One of the most striking quantum phenomena is superposition, where one particle simultaneously inhabits different states. Most methods to verify coherent superposition are indirect, in that they require the distinct states to be recombined. Here, we adapt an xor game, in which a “test” photon is placed in a superposition of two orthogonal spatial modes, and each mode is sent to separated parties who perform local measurements on their modes without reinterfering the original modes. We show that by using a second identical “measurement” photon the parties are nonetheless able to verify if the test photon was placed in coherent superposition of the two spatial modes. We then turn this game into a resource-efficient verification scheme, obtaining a confidence that the particle is superposed which approaches unity exponentially fast. We demonstrate our scheme using a single photon, obtaining a 99% confidence that the particle is superposed with only 37 copies. Our work shows the utility of xor games to verify quantum resources, allowing us to efficiently detect quantum superposition without reinterfering the superposed modes.","lang":"eng"}],"date_created":"2025-05-25T22:16:54Z","type":"journal_article","issue":"5","citation":{"mla":"Kun, Daniel, et al. “Direct and Efficient Detection of Quantum Superposition.” <i>Physical Review A</i>, vol. 111, no. 5, L050402, American Physical Society, 2025, doi:<a href=\"https://doi.org/10.1103/PhysRevA.111.L050402\">10.1103/PhysRevA.111.L050402</a>.","ama":"Kun D, Strömberg KT, Spagnolo M, Dakić B, Rozema LA, Walther P. Direct and efficient detection of quantum superposition. <i>Physical Review A</i>. 2025;111(5). doi:<a href=\"https://doi.org/10.1103/PhysRevA.111.L050402\">10.1103/PhysRevA.111.L050402</a>","short":"D. Kun, K.T. Strömberg, M. Spagnolo, B. Dakić, L.A. Rozema, P. Walther, Physical Review A 111 (2025).","chicago":"Kun, Daniel, Karl T Strömberg, Michele Spagnolo, Borivoje Dakić, Lee A. Rozema, and Philip Walther. “Direct and Efficient Detection of Quantum Superposition.” <i>Physical Review A</i>. American Physical Society, 2025. <a href=\"https://doi.org/10.1103/PhysRevA.111.L050402\">https://doi.org/10.1103/PhysRevA.111.L050402</a>.","apa":"Kun, D., Strömberg, K. T., Spagnolo, M., Dakić, B., Rozema, L. A., &#38; Walther, P. (2025). Direct and efficient detection of quantum superposition. <i>Physical Review A</i>. American Physical Society. <a href=\"https://doi.org/10.1103/PhysRevA.111.L050402\">https://doi.org/10.1103/PhysRevA.111.L050402</a>","ista":"Kun D, Strömberg KT, Spagnolo M, Dakić B, Rozema LA, Walther P. 2025. Direct and efficient detection of quantum superposition. Physical Review A. 111(5), L050402.","ieee":"D. Kun, K. T. Strömberg, M. Spagnolo, B. Dakić, L. A. Rozema, and P. Walther, “Direct and efficient detection of quantum superposition,” <i>Physical Review A</i>, vol. 111, no. 5. American Physical Society, 2025."},"publisher":"American Physical Society","volume":111,"article_processing_charge":"No","OA_type":"hybrid","acknowledgement":"This project has received funding from the European Union's Horizon 2020 and Horizon Europe research and innovation programmes under Grant Agreements No. 899368 (EPIQUS) and No. 101135288 (EPIQUE), the Marie Skłodowska-Curie Grant Agreement No. 956071 (AppQInfo), and the QuantERA II Programme under Grant Agreement No. 101017733 (PhoMemtor). The financial support by the Austrian Federal Ministry of Labour and Economy, the National Foundation for Research, Technology and Development, and the Christian Doppler Research Association is gratefully acknowledged. L.A.R. acknowledges support from the Erwin Schrödinger Center for Quantum Science & Technology (ESQ Discovery). This research was funded in whole or in part from the Austrian Science Fund (FWF) through [Grant No. 10.55776/COE1] (Quantum Science Austria), [Grant No. 10.55776/F71] (BeyondC), [Grant No. 10.55776/FG5] (Research Group 5), [Grant No. 10.55776/I6002] (PhoMemtor), and [Grant No. 10.55776/P36994] (Quantum Interference).","file_date_updated":"2025-05-28T09:16:03Z","scopus_import":"1","title":"Direct and efficient detection of quantum superposition","month":"05","external_id":{"arxiv":["2405.08065"]},"license":"https://creativecommons.org/licenses/by/4.0/","date_published":"2025-05-16T00:00:00Z"}