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.
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.
In recent years, round-robin-differential-phase-shift (RRDPS) quantum key distribution (QKD) has attracted great attention for its unique characteristics, i.e., the information leakage can be bounded without learning bit error rate. Though the RRDPS QKD has made a breakthrough, it is still a question of how RRDPS will perform with monitoring signal disturbance, e.g., decoy-state and error rate statistics are both used. Here, we present simulations to study RRDPS protocol while monitoring signal disturbance. To our excitement, when using the infinite decoy-states method, RRDPS protocol can outperform the commonly used Bennett and Brassard 1984 (BB84) protocol in terms of channel length under typical experimental parameters. In the case of finite decoy states, we find that only two decoy-states and one signal state are sufficient to obtain performance very close to the infinite decoy-states case. Our simulations prove that RRDPS is a competitive protocol in real-life situations.
Recently, a new type of protocol named Round-robin differential-phase-shift quantum key distribution (RRDPS QKD) was proposed, where the security can be guaranteed without monitoring conventional signal disturbances. The active decoy state method can be used in this protocol to overcome the imperfections of the source. But, it may lead to side channel attacks and break the security of QKD systems. In this paper, we apply the passive decoy state method to the RRDPS QKD protocol. Not only can the more environment disturbance be tolerated, but in addition it can overcome side channel attacks on the sources. Importantly, we derive a new key generation rate formula for our RRDPS protocol using passive decoy states and enhance the key generation rate. We also compare the performance of our RRDPS QKD to that using the active decoy state method and the original RRDPS QKD without any decoy states. From numerical simulations, the performance improvement of the RRDPS QKD by our new method can be seen.
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 an improved version of this so-called round-robin differential phase-shifting (RRDPS) protocol, in which both time and phase degrees of freedom are utilized to enlarge the Hilbert-space dimensionality, without increasing experimental complexity or relaxing security assumptions. We derive the security proofs of the round-robin differential phase-time-shifting (RRDPTS) protocol in the collective attack scenario, and benchmark it against RRDPS for different experimental parameters. Furthermore, a proof-of-concept experiment of the RRDPTS protocol, using weak coherent pulses and decoy state method, is demonstrated over 80 km of fiber link. Our results show that the RRDPTS protocol can achieve higher secret key rate in comparison with the RRDPS, in the condition of high quantum bit error rate.
Abstract Unlike traditional communication, quantum key distribution (QKD) can reach unconditional security and thus attracts intensive studies. Among all existing QKD protocols, round-robin-differential-phase-shift (RRDPS) protocol can be running without monitoring signal disturbance, which significantly simplifies its flow and improves its tolerance of error rate. Although several security proofs of RRDPS have been given, a tight finite-key analysis with a practical phase-randomized source is still missing. In this paper, we propose an improved security proof of RRDPS against the most general coherent attack based on the entropic uncertainty relation. What’s more, with the help of Azuma’s inequality, our proof can tackle finite-key effects primely. The proposed finite-key analysis keeps the advantages of phase randomization source and indicates experimentally acceptable numbers of pulses are sufficient to approach the asymptotical bound closely. The results shed light on practical QKD without monitoring signal disturbance.
Recently, a novel protocol named round-robin differential phase-shift (RRDPS) quantum key distribution [Nature 509, 475(2014)] has been proposed. It can estimate information leakage without monitoring bit error rate. In this paper, we study the performance of RRDPS using heralded single photon source (HSPS) without and with decoy-state method, then compare it with the performance of weak coherent pulses (WCPs). From numerical simulation, we can see that HSPS performs better especially for shorter packet and higher bit error rate. Moreover, we propose a general theory of decoy-state method for RRDPS protocol based on only three decoy states and one signal state. Taking WCPs as an example, the three-intensity decoy-state protocol can distribute secret keys over a distance of 128 km when the length of pulses packet is 32, which confirms great practical interest of our method.
Abstract The round-robin differential-phase-shift quantum key distribution (RRDPS-QKD) protocol could provide an effective way to estimate the leakage information without monitoring the signal disturbance. Moreover, the self-compensating property of plug-and-play (P&P) setup can eliminate the variations of phase or polarization in QKD procedure. In the paper, we introduce the P&P concept into RRDPS-QKD, and propose a QKD protocol, named P&P RRDPS-QKD protocol, to make the RRDPS-QKD scheme more practical. We analyze the security, and discuss the key generation rate with infinite-intensity decoy state method. The results show that the proposed protocol is a good solution to RRDPS-QKD protocol with untrusted sources. It has a high security and its key generation rate could be as good as the protocol with trusted sources when the average input photon number N is greater than 106. In addition, the proposed protocol has a high noise tolerance in comparison with P&P BB84-QKD protocol.