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Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Differential-phase-shift quantum key distribution

Kyo Inoue, Hiroki Takesue, Toshimori Honjo

Published Sep 9, 2007• 3 citations
Publisher

Abstract

A novel type of quantum key distribution (QKD) protocol, called DPS (differential-phase-shift) QKD, was proposed several years ago. A sender transmits a highly-attenuated coherent pulse train with {0, π} phase, and a receiver receives it with a one-bit delay Mach-Zehnder interferometer followed by photon detectors. A secret key is created from photon detection events, whose security is based on the fact that an eavesdropper cannot perfectly measure the phase information of a highly-attenuated coherent pulse train. This protocol has some features of simple setup, potential for a high key creation rate, and robustness against photon-number-splitting attack. This paper overviews DPS-QKD. The operation mechanism is described, and then some experimental efforts are introduced, featuring use of a glass waveguide Mach-Zehnder interferometer and advanced single-photon detectors. The highest key rate and the longest distance have been achieved with the DPS-QKD protocol. Some modified schemes are also presented, including that utilizing quantum entanglement, that using decoy pulses, and that using macroscopic coherent light.

DOI
10.1117/12.733442

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A novel type of quantum key distribution (QKD) protocol, called DPS (differential-phase-shift) QKD, was proposed several years ago. A sender transmits a highly-attenuated coherent pulse train with {0, π} phase, and a receiver receives it with a one-bit delay Mach-Zehnder interferometer followed by photon detectors. A secret key is created from photon detection events, whose security is based on the fact that an eavesdropper cannot perfectly measure the phase information of a highly-attenuated coherent pulse train. This protocol has some features of simple setup, potential for a high key creation rate, and robustness against photon-number-splitting attack. This paper overviews DPS-QKD. The operation mechanism is described, and then some experimental efforts are introduced, featuring use of a glass waveguide Mach-Zehnder interferometer and advanced single-photon detectors. The highest key rate and the longest distance have been achieved with the DPS-QKD protocol. Some modified schemes are also presented, including that utilizing quantum entanglement, that using decoy pulses, and that using macroscopic coherent light.
A unique quantum key distribution (QKD) protocol, called DPS (differential-phase-shift) QKD, has been proposed and developed at NTT and Osaka University, which utilizes a coherent pulse train instead of individual photons as in traditional QKD protocols such as BB84. Its security is based on the fact that every phase difference of a highlyattenuated coherent pulse train cannot be fully measured. This protocol has features of simple setup, potential for a high key creation rate, and robustness against photon-number-splitting attack. This paper presents recent research activities on DPS-QKD.
This paper presents a quantum key distribution (QKD) protocol named differential-quadrature-phase-shift (DQPS) QKD. A transmitter sends a coherent pulse train in which each pulse is phase modulated by ${0,\ensuremath{\pi}}$ ${\ensuremath{\pi}/2,3\ensuremath{\pi}/2}$, and a receiver measures it with either one of two asymmetric Mach-Zehnder interferometers having phase biases of 0 and $\ensuremath{\pi}/2$, respectively. This scheme is devised such that the idea of the conventional Bennett-Brassard 1984 protocol (BB84) is introduced to differential-phase-shift (DPS) QKD. Simulations show that the proposed scheme is robust against a sequential attack that is crucial eavesdropping to DPS-QKD.
In quantum key distribution (QKD), eavesdropping is generally detected based on bit errors resulting from eavesdropper attacks. This study proposes a QKD scheme for detecting eavesdropping based on the photon-detection rate instead of the bit error rate. The differential-phase-shift (DPS) QKD protocol, which transmits lasting weak coherent pulses, is modified such that decoy pulses with a large mean photon number are randomly inserted into a signal pulse sequence. With this modification, eavesdropping can be detected by monitoring the photon-detection rates at the time slots around the decoy pulses. The key-creation performance of the modified DPS-QKD system is evaluated, and the results indicate that the QKD distance is increased with the modification.
Quantum key distribution (QKD) has been studied as an ultimate method for secure communications, and it now is emerging as a technology that can be deployed in real fibre networks. Here, we present our QKD experiments based on the differential phase shift QKD (DPS-QKD) protocol. A DPS-QKD system has a simple configuration that is easy to implement with conventional optical communication components, and it is suitable for a high clock rate system. Moreover, although the DPS-QKD system is implemented with an attenuated laser source, it is inherently secure against strong eavesdropping attacks called photon number splitting attacks, which pose a serious threat to conventional QKD systems with attenuated laser sources. We also describe three types of single photon detectors that are suitable for high-speed, long-distance QKD: an upconversion detector, a superconducting single photon detector, and a sinusoidally gated InGaAs avalanche photodiode. We present our record setting QKD experiments that employed those detectors.
Quantum key distribution is used for secure communication between two parties for generation of secret key. Differential Phase Shift Quantum Key Distribution is a new and unique QKD protocol that is different from traditional ones, providing simplicity and practicality. This paper presents Delay Selected DPS-QKD scheme in which it uses a weak coherent pulse train, and features simple configuration and efficient use of the time domain. All detected photon participate to form a secure key bits and resulting in a higher key creation efficiency.