{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,11]],"date-time":"2026-04-11T01:05:18Z","timestamp":1775869518928,"version":"3.50.1"},"reference-count":39,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2023,6,27]],"date-time":"2023-06-27T00:00:00Z","timestamp":1687824000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"National Natural Science Foundation of China","award":["62001041"],"award-info":[{"award-number":["62001041"]}]},{"name":"National Natural Science Foundation of China","award":["62201012"],"award-info":[{"award-number":["62201012"]}]},{"name":"National Natural Science Foundation of China","award":["2022RC08"],"award-info":[{"award-number":["2022RC08"]}]},{"name":"National Natural Science Foundation of China","award":["IPOC2022ZT09"],"award-info":[{"award-number":["IPOC2022ZT09"]}]},{"name":"Fundamental Research Funds of BUPT","award":["62001041"],"award-info":[{"award-number":["62001041"]}]},{"name":"Fundamental Research Funds of BUPT","award":["62201012"],"award-info":[{"award-number":["62201012"]}]},{"name":"Fundamental Research Funds of BUPT","award":["2022RC08"],"award-info":[{"award-number":["2022RC08"]}]},{"name":"Fundamental Research Funds of BUPT","award":["IPOC2022ZT09"],"award-info":[{"award-number":["IPOC2022ZT09"]}]},{"name":"Fund of State Key Laboratory of Information Photonics and Optical Communications","award":["62001041"],"award-info":[{"award-number":["62001041"]}]},{"name":"Fund of State Key Laboratory of Information Photonics and Optical Communications","award":["62201012"],"award-info":[{"award-number":["62201012"]}]},{"name":"Fund of State Key Laboratory of Information Photonics and Optical Communications","award":["2022RC08"],"award-info":[{"award-number":["2022RC08"]}]},{"name":"Fund of State Key Laboratory of Information Photonics and Optical Communications","award":["IPOC2022ZT09"],"award-info":[{"award-number":["IPOC2022ZT09"]}]},{"name":"Stability Program of Science and Technology on Communication Security Laboratory (2022)","award":["62001041"],"award-info":[{"award-number":["62001041"]}]},{"name":"Stability Program of Science and Technology on Communication Security Laboratory (2022)","award":["62201012"],"award-info":[{"award-number":["62201012"]}]},{"name":"Stability Program of Science and Technology on Communication Security Laboratory (2022)","award":["2022RC08"],"award-info":[{"award-number":["2022RC08"]}]},{"name":"Stability Program of Science and Technology on Communication Security Laboratory (2022)","award":["IPOC2022ZT09"],"award-info":[{"award-number":["IPOC2022ZT09"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Symmetry"],"abstract":"<jats:p>In the continuous-variable quantum key distribution (CV-QKD) system with a local local oscillator (LLO), the center frequency of the sender and the receiver\u2019s source are not exactly the same and a certain frequency drift exists over time, resulting in the frequency of the signal received near the intermediate frequency. Therefore, the LLO system needs an intermediate-frequency balanced homodyne detector (BHD), which needs better symmetry of the arms of the BHD, to obtain the less-common mode noise. Moreover, the traditional intermediate-frequency receiver in classical communication is not available in the CV-QKD system because of the low quantum-to-classical noise ratio. In view of this, in this paper, we construct a broadband intermediate-frequency BHD based on ratio frequency and integrated circuit technology, whose bandwidth can exceed 270 MHz and whose quantum-to-classical noise ratio can reach 14.9 dB. Meanwhile, the BHD has an excellent linear performance with a gain of 22.4 k. By adopting our intermediate-frequency BHD, the secret key rate of the pilot-sequential Gaussian modulated coherent state CV-QKD system with an LLO can reach over 430.8 kbps of 60 km at the standard fiber length, which paves the way to achieve a high-performance LLO CV-QKD system with intermediate-frequency BHD.<\/jats:p>","DOI":"10.3390\/sym15071314","type":"journal-article","created":{"date-parts":[[2023,6,27]],"date-time":"2023-06-27T01:42:02Z","timestamp":1687830122000},"page":"1314","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["High-Performance Intermediate-Frequency Balanced Homodyne Detector for Local Local Oscillator Continuous-Variable Quantum Key Distribution"],"prefix":"10.3390","volume":"15","author":[{"given":"Dengke","family":"Qi","sequence":"first","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"},{"name":"School of Cyberspace Security, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-2132-0065","authenticated-orcid":false,"given":"Xiangyu","family":"Wang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-8343-8029","authenticated-orcid":false,"given":"Ziyang","family":"Chen","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Advanced Optical Communication Systems and Networks, School of Electronics, and Center for Quantum Information Technology, Peking University, Beijing 100871, China"}]},{"given":"Yueming","family":"Lu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"},{"name":"School of Cyberspace Security, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]},{"given":"Song","family":"Yu","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China"}]}],"member":"1968","published-online":{"date-parts":[[2023,6,27]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"1012","DOI":"10.1364\/AOP.361502","article-title":"Advances in quantum cryptography","volume":"12","author":"Pirandola","year":"2020","journal-title":"Adv. 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