Optics Letters

High-speed robust polarization modulation for quantum key distribution

Yang Li, Yu-Huai Li, Hongbo Xie, Zheng-Ping Li, Xiao Qiang Jiang, Wenqi Cai, Ji-Gang Ren, Juan Yin, Sheng‐Kai Liao, Cheng-Zhi Peng

Published Oct 22, 2019• 67 citations

Publisher

Abstract

Polarization modulation plays a key role in polarization-encoding quantum key distribution (QKD). Here, we report a new, to the best of our knowledge, polarization modulation scheme based on an inherently stable Sagnac interferometer. The presented scheme is free of polarization mode dispersion and calibration as well as insensitive to environmental influences. Successful experiments at a repetition frequency of 1.25 GHz have been conducted to demonstrate the feasibility and stability of the scheme. The measured average quantum bit-error rate of the four polarization states is as low as 0.27% for 80 consecutive minutes without any adjustment. This high-speed intrinsically stable polarization modulation can be widely applied to many polarization-encoding QKD systems, such as BB84, MDI, etc.

DOI: 10.1364/ol.44.005262

Related papers

High-speed and robust modulation of arbitrary polarization states based on Sagnac interferometer for quantum key distribution

Zexu Wang, Huaxing Xu, Bo Liu +3 more

In polarization-encoding quantum key distribution (QKD) systems, achieving high-speed, robust, and low-error polarization modulation helps to increase the secure key rate (SKR). Moreover, the advanced QKD protocols place higher demands on the system’s photon preparation capability, which implies providing additional polarization states for practical implementation. Here, we redesign the Sagnac interferometer and utilize the non-reciprocity of the lithium niobate modulator to eliminate the reverse modulation that limits the modulation speed. The proposed scheme enables high-speed, robust, and low-error modulation with arbitrary polarization states. The average bit error rate (BER) for the 10 min measurement is 0.2332% with a system repetition frequency of 16.5 GHz.

Tenth International Conference on Information Optics and PhotonicsDec 8, 20250 citations

Intrinsically Stable 2-GHz Polarization Modulation for Satellite-Based Quantum Key Distribution

Wenbin Luo, Yang Li, Yuhuai Li +7 more

Satellite-based quantum key distribution (QKD) has made significant strides in the past few years, and an international space race toward practical quantum networks has begun. Being one major encoding method, highly robust, high-performance and miniaturized polarization modulation is critical to meet the needs of future satellite applications. Here, we employ the Sagnac-based method to realize inherent-stable polarization modulation and propose a novel optical design to achieve a state-of-the-art repetition rate of 2 GHz. This value approaches the theoretical repetition frequency limit with commercially-available phase modulators. Furthermore, the polarization encoder is miniaturized into a robust 6.0 cm × 6.5 cm module and two commercially mature phase modulators. A 90-min consecutive test was successfully performed, verifying the robustness of this scheme with an average quantum bit error rate as low as 0.42%. The presented intrinsically stable high-speed polarization modulation provides an effective solution for future satellite applications.

IEEE photonics journalSep 26, 20229 citations

Time-bin phase-encoding quantum key distribution using Sagnac-based optics and compatible electronics

yan-lin tang, Chun Zhou, Dongdong Li +18 more

In this work, we present a new time-bin phase-encoding quantum key distribution (QKD), where the transmitter utilizes an inherently stable Sagnac-type interferometer, and has comparable electrical requirements to existing polarization or phase encoding schemes. This approach does not require intensity calibration and is insensitive to environmental disturbances, making it both flexible and high-performing. We conducted experiments with a compact QKD system to demonstrate the stability and secure key rate performance of the presented scheme. The results show a typical secure key rate of 6.2 kbps@20 dB and 0.4 kbps@30 dB with channel loss emulated by variable optical attenuators. A continuous test of 120-km fiber spool shows a stable quantum bit error rate of the time-bin basis within 0.4%∼0.6% over a consecutive 9-day period without any adjustment. This intrinsically stable and compatible scheme of time-bin phase encoding is extensively applicable in various QKD experiments, including BB84 and measurement-device-independent QKD.

Optics ExpressJul 5, 202324 citations

A High-Speed Stable Polarization Encoder for Quantum Key Distribution

Ju Li, Zexu Wang, Changlei Wang +4 more

We report a high-speed polarization encoder which can be applied for quantum key distribution, resulting in an average bit error rate (BER) below 0.1% at a repetition frequency of 10 GHz under interference-free measurements.

Conference on Lasers and Electro-Optics Pacific Rim (CLEO-PR)Aug 4, 20240 citations

10 GHz robust polarization modulation towards high-speed satellite-based quantum communication

Ze-Xu Wang, Huaxing Xu, Ju Li +9 more

In practical satellite-based quantum key distribution (QKD) systems, the preparation and transmission of polarization-encoding photons suffer from complex environmental effects and high channel loss. Consequently, the hinge to enhancing the secure key rate (SKR) lies in achieving robust, low-error, and high-speed polarization modulation. Although the schemes that enable self-compensation demonstrate remarkable robustness, their modulation speed is limited to around 2 GHz to prevent the interaction between the electrical signal and the reverse optical pulses. Here, we utilize the non-reciprocity of the lithium niobate modulators and eliminate the modulation on the reverse optical pulses. This characteristic is widely available in the radio-frequency band, allowing the modulation speed to no longer be limited by the self-compensating optics and enabling further increases. The measured average intrinsic quantum bit error rate of the four polarization states at 10 GHz system repetition frequency is as low as 0.53% over 10 min without any compensation. The simulation results show that our scheme can maintain a SKR of about 5 kbps even at the extreme communication distances between the satellite and the earth. Our work can be efficiently applied in high-speed, high-loss satellite-based quantum communication scenarios.

arXiv:2411.08358EPJ Quantum TechnologyApr 11, 202511 citations

Proof-of-principle demonstration of measurement-device-independent quantum key distribution based on intrinsically stable polarization-modulated units

Yiping Yuan, Cong Du, Qi-Qi Shen +5 more

The experimental demonstration of measurement-device-independent quantum key distribution (MDI-QKD) has been widely demonstrated. Thus far, several experimental groups have implemented polarization encoding MDI-QKD but with manual polarization controllers, or polarization modulators that make circular polarization states unstable. Here, we apply an intrinsically stable polarization-modulated unit (PMU) to MDI-QKD so that Alice and Bob can modulate four BB84 polarization states, all of which can be kept stable from even the harsh environment. Moreover, our PMU can provide two operational polarization encoding modes suitable to different application scenarios. A proof-of-principle demonstration of MDI-QKD based on our PMU is implemented with an interference visibility of 46.6%, an average quantum bit error rate of 1.49% for the Z basis and the secure key rate of 4.25 × 10−6 bits per pulse. The proposed study is helpful for building polarization encoding MDI-QKD systems with better stability.

Optics ExpressMar 23, 20209 citations