Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier

Abstract The type of system employing continuous variables, such as light field quadrature for signal modulation, is an important branch for quantum key distribution. Achieving a high key rate using quantum key distribution technology is beneficial for realizing more frequent key updates or enabling...

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Main Authors: Jinpeng Liao, Zhirong Chen, Jintao Wang, Hao Xiao, Xiaojie Guo, Zhaohui Li, Dawei Wang
Format: Article
Language:English
Published: Nature Portfolio 2025-06-01
Series:npj Quantum Information
Online Access:https://doi.org/10.1038/s41534-025-01060-7
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author Jinpeng Liao
Zhirong Chen
Jintao Wang
Hao Xiao
Xiaojie Guo
Zhaohui Li
Dawei Wang
author_facet Jinpeng Liao
Zhirong Chen
Jintao Wang
Hao Xiao
Xiaojie Guo
Zhaohui Li
Dawei Wang
author_sort Jinpeng Liao
collection DOAJ
description Abstract The type of system employing continuous variables, such as light field quadrature for signal modulation, is an important branch for quantum key distribution. Achieving a high key rate using quantum key distribution technology is beneficial for realizing more frequent key updates or enabling one-time pad encryption for high-speed communication tasks. However, the deficiencies of typical large-bandwidth balanced photodetectors prevent the continuous variable quantum key distribution from matching the speed of state-of-the-art classical optical communications. Previous attempts to improve the key rate have focused on designing and manufacturing high-speed balanced photodetectors. It is well known that phase-sensitive amplifiers also improve the performance of balanced photodetectors and thus the performance of key distribution, but the concept remains purely theoretical. Here, for the first time, we experimentally demonstrate a high-speed continuous-variable quantum key distribution operating with a 10 GHz balanced photodetector enhanced by phase-sensitive amplification and detection. A conjugated multi-mode continuous variable protocol is used to accommodate the phase-sensitive operations. The optical amplifier offers a 10 dB increase in the photodetector’s clearance (quantum noise over electrical noise) and improves the detection efficiency from 72% to 96%, thus enabling an overall 248.9 Mb/s key distribution rate through a 16.7 km field-deployed optical fiber.
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spelling doaj-art-6d4b5ded548f4cc78b80936126d0c4ca2025-08-20T02:37:34ZengNature Portfolionpj Quantum Information2056-63872025-06-011111710.1038/s41534-025-01060-7Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifierJinpeng Liao0Zhirong Chen1Jintao Wang2Hao Xiao3Xiaojie Guo4Zhaohui Li5Dawei Wang6Guangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan UniversityGuangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Optoelectronic Information Processing Chips and Systems, School of Electronics and Information Technology, Sun Yat-sen UniversityAbstract The type of system employing continuous variables, such as light field quadrature for signal modulation, is an important branch for quantum key distribution. Achieving a high key rate using quantum key distribution technology is beneficial for realizing more frequent key updates or enabling one-time pad encryption for high-speed communication tasks. However, the deficiencies of typical large-bandwidth balanced photodetectors prevent the continuous variable quantum key distribution from matching the speed of state-of-the-art classical optical communications. Previous attempts to improve the key rate have focused on designing and manufacturing high-speed balanced photodetectors. It is well known that phase-sensitive amplifiers also improve the performance of balanced photodetectors and thus the performance of key distribution, but the concept remains purely theoretical. Here, for the first time, we experimentally demonstrate a high-speed continuous-variable quantum key distribution operating with a 10 GHz balanced photodetector enhanced by phase-sensitive amplification and detection. A conjugated multi-mode continuous variable protocol is used to accommodate the phase-sensitive operations. The optical amplifier offers a 10 dB increase in the photodetector’s clearance (quantum noise over electrical noise) and improves the detection efficiency from 72% to 96%, thus enabling an overall 248.9 Mb/s key distribution rate through a 16.7 km field-deployed optical fiber.https://doi.org/10.1038/s41534-025-01060-7
spellingShingle Jinpeng Liao
Zhirong Chen
Jintao Wang
Hao Xiao
Xiaojie Guo
Zhaohui Li
Dawei Wang
Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
npj Quantum Information
title Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
title_full Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
title_fullStr Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
title_full_unstemmed Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
title_short Experimental demonstration of high-speed continuous variable quantum key distribution enhanced by phase-sensitive amplifier
title_sort experimental demonstration of high speed continuous variable quantum key distribution enhanced by phase sensitive amplifier
url https://doi.org/10.1038/s41534-025-01060-7
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