Performance of passive decoy-state quantum key distribution with mismatched local detectors

In quantum key distribution (QKD), passive decoy-state method can simplify the intensity modulation and reduce some of side-channel information leakage and modulation errors. It is usually implemented with a heralded single-photon source. In [Physical Review A 96, 032312 (2016)], a novel passive decoy-state method is proposed by Wang et al., which uses two local detectors to generate more detection events for tightly estimating channel parameters. However, in original scheme, the two local detectors are assumed to be identical, including same detection efficiency and dark count rate, which is often not satisfied in realistic experiment. Therefore, in this paper, we construct a model for this passive decoy-state QKD scheme with two mismatched detectors and explore the effect on QKD performance with certain parameter. We also take the finite-size effect into consideration, showing the performance with statistical fluctuations. The results show that the efficiencies of local detectors affect the key rate more obviously than dark count rates. Our work provides a reference value for realistic QKD system.

Intensity modulator for secure, stable, and high-performance decoy-state quantum key distribution

The decoy-state method substantially improves the performance of quantum key distribution (QKD) and perfectly solves crucial issues caused by multiphoton pulses. In recent years, the decoy-state method has occupied a key position in practicality, and almost all the QKD systems have employed the decoy-state method. However, the imperfections of traditional intensity modulators limit the performance of the decoy-state method and bring side channels. In this work, a special intensity modulator and its accompanying modulation method are designed and experimentally verified for the secure, stable, and high-performance decoy-state QKDs. The experimental result indicates that its stable and adjustable intensities, convenient two-level modulation, inherently high speed, and compact structure is extremely fit for future trends and will help the decoy-state method to be perfectly applied to QKD systems.

Decoy state quantum-key-distribution by using odd coherent states without monitoring signal disturbance

Recently, a novel quantum-key-distribution (QKD) protocol, called Round-robin-differential-phase-shift (RRDPS) QKD, has been proposed to share a secure key without monitoring the signal disturbance. In this paper, we propose a decoy state RRDPS-QKD protocol with odd coherent states (OCS). We implement a one-intensity decoy state method into the RRDPS-QKD with OCS to estimate the key rate. The results show that both the maximum transmission distance and the key rate of our protocol are significantly improved. Moreover, only one-intensity decoy state is sufficient for the protocol to approach the asymptotic limit with infinite decoy states.