Experimental Passive Round-Robin Differential Phase-Shift Quantum Key Distribution

通过轮询稀疏化实现容错且完全可寻址的酉逻辑门

Fault-tolerant and fully addressable unitary logical gates via round-robin sparsification

本研究针对量子LDPC码，提出基于轮询稀疏化的低深度酉电路，实现完全可寻址且容错的两量子比特克利福德门，并通过多种码的数值模拟验证其普遍适用性。

Round-robin differential phase-time-shifting protocol for quantum key distribution: theory and experiment

Quantum key distribution (QKD) allows the establishment of common cryptographic keys among distant parties. Many of the QKD protocols that were introduced in the past involve the challenge of monitoring the signal disturbance over the communication line, in order to evaluate the information leakage to a potential eavesdropper. Recently, a QKD protocol that circumvents the need for monitoring signal disturbance, has been proposed and demonstrated in initial experiments. Here, we propose a new version of this so-called round-robin differential phase-shifting (RRDPS) protocol, in which both time …

A security proof of the round-robin differential phase shift quantum key distribution protocol based on the signal disturbance

The round-robin differential phase shift (RRDPS) quantum key distribution (QKD) protocol is a unique quantum key distribution protocol whose security has not been understood through an information-disturbance trade-off relation, and a sufficient amount of privacy amplification was given independently of signal disturbance. Here, we discuss the security of the RRDPS protocol in the asymptotic regime when a good estimate of the bit error rate is available as a measure of signal disturbance. The uniqueness of the RRDPS protocol shows up as a peculiar form of information-disturbance trade-off curv…

Round robin differential phase shift quantum key distribution with yes-no detectors only

In the original round-robin differential-phase-shift (RRDPS) quantum key distribution and its improved method, the photon-number-resolving detectors are must for the security. We present a RRDPS protocol with yes-no detectors only. We get the upper bounds of mutual information of Alice and Eve, and Bob and Eve, and the formula of key rate. Our main idea is to divide all counts into two classes, the counts due to the odd number photons of incident detectors and the counts due to the even number photons of incident detectors. The fact that the bit-flip error rate of the later class is certainly …

Security of round-robin differential-phase-shift quantum key distribution protocol with correlated light sources

Among various quantum key distribution (QKD) protocols, the round-robin differential-phase-shift (RRDPS) protocol has a unique feature that its security is guaranteed without monitoring any statistics. Moreover, this protocol has a remarkable property of being robust against source imperfections assuming that the emitted pulses are independent. Unfortunately, some experiments confirmed the violation of the independence due to pulse correlations, and therefore the lack of a security proof without taking into account this effect is an obstacle for the security. In this paper, we prove that the R…

Practical round-robin differential-phase-shift quantum key distribution

The security of quantum key distribution (QKD) relies on the Heisenberg uncertainty principle, with which legitimate users are able to estimate information leakage by monitoring the disturbance of the transmitted quantum signals. Normally, the disturbance is reflected as bit flip errors in the sifted key; thus, privacy amplification, which removes any leaked information from the key, generally depends on the bit error rate. Recently, a round-robin differential-phase-shift QKD protocol for which privacy amplification does not rely on the bit error rate [Nature 509, 475 (2014)] was proposed. The…

Round-robin-differential-phase-shift quantum key distribution with and without monitoring signal disturbance

Round-robin-differential-phase (RRDPS) quantum key distribution (QKD) protocol has attracted intensive studies due to its distinct security characteristic, e.g., information leakage in RRDPS can be bounded without learning error rate of key bits. Nevertheless, its implementation is still far from practical due to the complication of its measurement device. Moreover, on the theoretical side, its security is still not clear in view of optimal attack. Here, by observing a potential phase randomization of the encoding states and its connection with eavesdropper's ancilla, we develop a theory to bo…

轮询差分相移协议中的高维编码

High-dimensional Encoding in the Round-Robin Differential-Phase-Shift Protocol

本研究提出将轮询差分相移量子密钥分发协议扩展到任意大编码字母表的方法，结合高维与差分相移QKD的编码优势，通过概念验证实验验证框架可适配不同实验条件，为弥合两类量子通信方案差距提供新思路。

Round-Robin Differential Phase-Shift Quantum Key Distribution with Twisted Photons

Quantum key distribution (QKD) offers the possibility for two individuals to communicate a securely encrypted message. From the time of its inception in 1984 by Bennett and Brassard, QKD has been the result of intense research. One technical challenge is the monitoring of signal disturbance in a QKD system to bound the information leakage towards an unwanted eavesdropper. Recently, the round-robin differential phase-shift (RRDPS) protocol, which encodes bits of information in a high-dimensional state space, was proposed to solve this exact problem. Since its introduction, many realizations of …

Experimental round-robin differential phase-shift quantum key distribution

In conventional quantum key distribution (QKD) protocols, security is guaranteed by estimating the amount of leaked information through monitoring signal disturbance, which, in practice, is generally caused by environmental noise and device imperfections rather than eavesdropping. Such estimation therefore tends to overrate the amount of leaked information in practice, leads to a fundamental threshold of the bit error rate. The threshold becomes a bottleneck of the development of practical QKD systems. In classical communication, according to Shannon's communication theory, information can tra…

Solving Large Break Minimization Problems in a Mirrored Double Round-robin Tournament Using Quantum Annealing

Quantum annealing (QA) has gained considerable attention because it can be applied to combinatorial optimization problems, which have numerous applications in logistics, scheduling, and finance. In recent years, research on solving practical combinatorial optimization problems using them has accelerated. However, researchers struggle to find practical combinatorial optimization problems, for which quantum annealers outperform other mathematical optimization solvers. Moreover, there are only a few studies that compare the performance of quantum annealers with one of the most sophisticated mathe…

Detector-decoy quantum key distribution without monitoring signal disturbance

The round-robin differential phase-shift quantum key distribution protocol provides a secure way to exchange private information without monitoring conventional disturbances and still maintains a high tolerance of noise, making it desirable for practical implementations of quantum key distribution. However, photon number resolving detectors are required to ensure that the detected signals are single photons in the original protocol. Here, we adopt the detector-decoy method and give the bounds to the fraction of detected events from single photons. Utilizing the advantages of the protocol, we p…