The Experts below are selected from a list of 10626 Experts worldwide ranked by ideXlab platform

Yoshihisa Yamamoto - One of the best experts on this subject based on the ideXlab platform.

Toshimori Honjo - One of the best experts on this subject based on the ideXlab platform.

Dexiu Huang - One of the best experts on this subject based on the ideXlab platform.

  • reconfigurable all optical logic gates for multi input Differential Phase Shift keying signals design and experiments
    Journal of Lightwave Technology, 2009
    Co-Authors: Deming Liu, Dexiu Huang
    Abstract:

    Differential Phase-Shift keying (DPSK) signals are promising candidate for the long-haul transmission systems. However, the development of the all-optical signal processing techniques for the DPSK signals is still in its infancy, especially the all-optical logic operations. In this work, a general scheme for reconfigurable logic gates for multi-input DPSK signals with integration possibility is proposed. Benefiting from the optical logic minterms developed by two kinds of optical devices, i.e., optical delay interferometers and semiconductor optical amplifiers (SOAs), target logic functions can be realized by combining specific minterms together. The scheme is reconfigured by changing the Phase control of the delay interferometers or the input wavelengths. The latter approach was adopted in the experimental trials. Although the outputs of the scheme are on-off keying (OOK) signals, the data format is compatible with all-optical decision circuits where OOK format is preferred. Two- and three-input experiments are carried out at 20 Gbit/s with nonreturn-to-zero DPSK signals. Various logic operations are demonstrated, including full sets of two- and three-input minterms, AND, NOR, XOR, and XNOR logic operations where the AND and NOR logic are derived simultaneously and the XOR and XNOR logic are convertible. The optical SNR as well as the Q-factor of the two- and three-input results are measured and compared. It shows that the input powers to the SOAs are critical in achieving good extinction ratio and the Q-factor of logic results degrades when several minterms are combined. The recovery time of the SOAs need to be optimized as well. Finally, the scaling issues of the scheme are discussed.

  • dynamic analysis of all optical wavelength conversion of Differential Phase Shift keyed signals based on semiconductor optical amplifier mach zehnder interferometer
    Journal of Lightwave Technology, 2009
    Co-Authors: Wei Hong, Junqiang Sun, Xinliang Zhang, Dexiu Huang
    Abstract:

    All-optical wavelength conversion of Differential Phase-Shift keyed (DPSK) signals based on semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is simulated and analyzed. The results show that, to obtain both good quality of the converted signal and high conversion efficiency, Phase difference between the upper and lower arms of MZI should be near ?, which suggests strong cross-Phase-modulation (XPM) and cross-gain-modulation (XGM) for optimized operation of this wavelength converter, while weak XPM and XGM will lead to sacrifice of conversion efficiency. The results also show larger wavelength up-conversion range, and suggest non-return-to-zero (NRZ) format for 10 Gb/s operation while return-to-zero (RZ) format for 40 Gb/s operation. Besides, short carrier lifetime is preferred for high-speed applications and appropriate linewidth enhancement factor can be utilized to mitigate amplitude fluctuation of the converted signal if the carrier lifetime is not short enough.

  • ultrafast all optical three input boolean xor operation for Differential Phase Shift keying signals using periodically poled lithium niobate
    Optics Letters, 2008
    Co-Authors: Jing Wang, Xinliang Zhang, Dexiu Huang, Junqiang Sun, Martin M Fejer
    Abstract:

    We propose and demonstrate that periodically poled lithium niobate (PPLN) can act as an ultrafast three-input XOR gate for Differential Phase-Shift keying (DPSK) signals based on cascaded sum- and difference-frequency generation. PPLN-based all-optical three-input Boolean XOR operations for 20 Gbits/s return-to-zero DPSK (RZ-DPSK), 40 Gbits/s RZ-DPSK, and 20 Gbits/s non-return-to-zero DPSK signals are all successfully verified in the experiment.

Kyo Inoue - One of the best experts on this subject based on the ideXlab platform.

  • field trial of Differential Phase Shift quantum key distribution using polarization independent frequency up conversion detectors
    Optics Express, 2007
    Co-Authors: Toshimori Honjo, Shuto Yamamoto, Takashi Yamamoto, H Kamada, Yoshiki Nishida, Osamu Tadanaga, Masaki Asobe, Kyo Inoue
    Abstract:

    We report a field trial of Differential Phase Shift quantum key distribution (QKD) using polarization independent frequency up-conversion detectors. A frequency up-conversion detector is a promising device for achieving a high key generation rate when combined with a high clock rate QKD system. However, its polarization dependence prevents it from being applied to practical QKD systems. In this paper, we employ a modified polarization diversity configuration to eliminate the polarization dependence. Applying this method, we performed a long-term stability test using a 17.6-km installed fiber. We successfully demonstrated stable operation for 6 hours and achieved a sifted key generation rate of 120 kbps and an average quantum bit error rate of 3.14 %. The sifted key generation rate was not the estimated value but the effective value, which means that the sifted key was continuously generated at a rate of 120 kbps for 6 hours.

  • Differential Phase Shift quantum key distribution experiment over 105 km fibre
    New Journal of Physics, 2005
    Co-Authors: Toshimori Honjo, Kyo Inoue, Yoshihisa Yamamoto, Carsten Langrock, Martin M Fejer
    Abstract:

    We report a quantum key distribution experiment based on the Differential Phase Shift keying (DPSK) protocol with a Poissonian photon source, in which secure keys were generated over >100 km fibre for the first time. We analysed the security of the DPSK protocol and showed that it is robust against strong attacks by Eve, including a photon number splitting attack. To implement this protocol, we developed a new detector for the 1.5 μm band based on frequency up-conversion in a periodically poled lithium niobate waveguide followed by an Si avalanche photodiode. The use of detectors increased the sifted key generation rate up to >1 Mbit s−1 over 30 km fibre, which is two orders of magnitude larger than the previous record.

  • Differential Phase Shift quantum key distribution experiment over 105 km fibre
    arXiv: Quantum Physics, 2005
    Co-Authors: Hiroki Takesue, Eleni Diamanti, Kyo Inoue, Toshimori Honjo, Yoshihisa Yamamoto, Carsten Langrock, Martin M Fejer
    Abstract:

    Since several papers appeared in 2000, the quantum key distribution (QKD) community has been well aware that photon number splitting (PNS) attack by Eve severely limits the secure key distribution distance in BB84 QKD systems with Poissonian photon sources. In attempts to solve this problem, entanglement-based QKD, single-photon based QKD, and entanglement swapping-based QKD, have been studied in recent years. However, there are many technological difficulties that must be overcome before these schemes can become practical systems. Here we report a very simple QKD system, in which secure keys were generated over >100 km fibre for the first time. We used an alternative protocol of Differential Phase Shift keying (DPSK) but with a Poissonian source. We analysed the security of the DPSK protocol and showed that it is robust even against hybrid attacks including collective PNS attack over consecutive pulses, intercept-and-resend (I-R) attack and beamsplitting (BS) attack, because of the non-deterministic collapse of a wavefunction in a quantum measurement. To implement this protocol, we developed a new detector for the 1.5 um band based on frequency up-conversion in a periodically poled lithium niobate (PPLN) waveguide followed by a Si avalanche photodiode (APD). The use of the new detectors increased the sifted key generation rate up to > 1 Mbit/s over 30 km fibre, which is two orders of magnitude larger than the previous record.

  • robustness of Differential Phase Shift quantum key distribution against photon number splitting attack
    Physical Review A, 2005
    Co-Authors: Kyo Inoue, Toshimori Honjo
    Abstract:

    A photon-number-splitting (PNS) attack against Differential-Phase-Shift (DPS) quantum key distribution (QKD) is described. In the conventional 1984 Bennett-Brassard protocol, using weak laser light, the PNS attacks, which involve installing a lossless transmission line and blocking pulses from which extra photons cannot be picked up, impose a limit on the transmission distance. In contrast, use of a coherent pulse train in DPS QKD prevents the PNS attack and removes the distance limitation imposed by it. We carried out a DPS QKD experiment that simulated the situation where some pulses are blocked. The result showed that extra bit errors are induced in an eavesdropped condition, indicating the robustness of DPS QKD against PNS attacks.

  • Differential Phase Shift quantum key distribution experiment with a planar light wave circuit mach zehnder interferometer
    Optics Letters, 2004
    Co-Authors: Toshimori Honjo, Kyo Inoue, Hiroshi Takahashi
    Abstract:

    A Differential-Phase-Shift quantum key distribution experiment was carried out with a planar light-wave circuit (PLC) Mach–Zehnder interferometer. This scheme has two advantages: it requires no polarization control and has a high repetition frequency, provided that a stable interferometer is available. Stable polarization-insensitive operation was achieved with an interferometer fabricated by PLC technology. Raw key creation at a rate of 3076 bits/s with a 5.0% quantum bit-error rate was achieved over 20 km of fiber. The stability of the PLC interferometer was examined.

Kiyoshi Tamaki - One of the best experts on this subject based on the ideXlab platform.

  • information theoretic security proof of Differential Phase Shift quantum key distribution protocol based on complementarity
    Quantum Science and Technology, 2018
    Co-Authors: Akihiro Mizutani, Toshihiko Sasaki, Go Kato, Yuki Takeuchi, Kiyoshi Tamaki
    Abstract:

    We prove the information-theoretic security of the Differential-Phase-Shift (DPS) quantum key distribution (QKD) protocol in the asymptotic regime based on the complementarity approach (arXiv:0704.3661 (2007)). Our security proof provides a slightly better key generation rate compared to the one derived in the previous security proof in (arXiv:1208.1995 (2012)) that is based on the Shor?Preskill approach?(Shor and Preskill 2000 Phys. Rev. Lett. 85 441). This improvement is obtained because the complementarity approach can employ more detailed information on Alice's sending state in estimating the leaked information to an eavesdropper. Moreover, we remove the necessity of the numerical calculation that was needed in the previous analysis to estimate the leaked information. This leads to an advantage that our security proof enables us to evaluate the security of the DPS protocol with any block size. This paper highlights one of the fundamental differences between the Shor?Preskill and the complementarity approaches.

  • information theoretic security proof of Differential Phase Shift quantum key distribution protocol based on complementarity
    arXiv: Quantum Physics, 2017
    Co-Authors: Akihiro Mizutani, Toshihiko Sasaki, Go Kato, Yuki Takeuchi, Kiyoshi Tamaki
    Abstract:

    We show the information-theoretic security proof of the Differential-Phase-Shift (DPS) quantum key distribution (QKD) protocol based on the complementarity approach [arXiv:0704.3661 (2007)]. Our security proof provides a slightly better key generation rate compared to the one derived in the previous security proof in [arXiv:1208.1995 (2012)] that is based on the Shor-Preskill approach [Phys. Rev. Lett. ${\bf 85}$, 441 (2000)]. This improvement is obtained because the complementarity approach can employ more detailed information on Alice's sending state in estimating the leaked information to an eavesdropper. Moreover, we remove the necessity of the numerical calculation that was needed in the previous analysis to estimate the leaked information. This leads to an advantage that our security proof enables us to evaluate the security of the DPS protocol with any block size. This paper highlights one of the fundamental differences between the Shor-Preskill and the complementarity approaches.

  • Differential Phase Shift quantum key distribution protocol with a small number of random delays
    Physical Review A, 2017
    Co-Authors: Yuki Hatakeyama, Nobuyuki Imoto, Akihiro Mizutani, Go Kato, Kiyoshi Tamaki
    Abstract:

    The Differential-Phase-Shift (DPS) quantum key distribution (QKD) protocol was proposed aiming at simple implementation, but it can tolerate only a small disturbance in a quantum channel. The round-robin DPS (RRDPS) protocol could be a good solution for this problem, which in fact can tolerate even up to $50\%$ of a bit error rate. Unfortunately, however, such a high tolerance can be achieved only when we compromise the simplicity, i.e., Bob's measurement must involve a large number of random delays ($|\mathcal{R}|$ denotes its number), and in a practical regime of $|\mathcal{R}|$ being small, the tolerance is low. In this paper, we propose a new DPS protocol to achieve a higher tolerance than the one in the original DPS protocol, in which the measurement setup is less demanding than the one of the RRDPS protocol for the high tolerance regime. We call the new protocol the small-number-random DPS (SNRDPS) protocol, and in this protocol, we add only a small amount of randomness to the original DPS protocol, i.e., $2\leq|\mathcal{R}|\leq10$. In fact, we found that the performance of the SNRDPS protocol is significantly enhanced over the original DPS protocol only by employing a few additional delays such as $|\mathcal{R}|=2$. Also, we found that the key generation rate of the SNRDPS protocol outperforms the RRDPS protocol without monitoring the bit error rate when it is less than $5\%$ and $|\mathcal{R}|\leq10$. Our protocol is an intermediate protocol between the original DPS protocol and the RRDPS protocol, and it increases the variety of the DPS-type protocols with quantified security.

  • experimental transmission of quantum digital signatures over 90 km of installed optical fiber using a Differential Phase Shift quantum key distribution system
    Optics Letters, 2016
    Co-Authors: Robert J Collins, Toshimori Honjo, Kiyoshi Tamaki, Ryan Amiri, Mikio Fujiwara, Kaoru Shimizu, Masahiro Takeoka, Erika Andersson, Gerald S Buller, Masahide Sasaki
    Abstract:

    Quantum digital signatures (QDSs) apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution (QKD). Previous experimental demonstrations have been limited to transmission distances of less than 5 km of optical fiber in a laboratory setting. Here we report, to the best of our knowledge, the first demonstration of QDSs over installed optical fiber, as well as the longest transmission link reported to date. This demonstration used a 90 km long Differential Phase Shift QKD to achieve approximately one signed bit per second, an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations.

  • experimental transmission of quantum digital signatures over 90 km of installed optical fiber using a Differential Phase Shift quantum key distribution system
    arXiv: Quantum Physics, 2016
    Co-Authors: Robert J Collins, Toshimori Honjo, Kiyoshi Tamaki, Ryan Amiri, Mikio Fujiwara, Kaoru Shimizu, Masahiro Takeoka, Erika Andersson, Gerald S Buller, Masahide Sasaki
    Abstract:

    Quantum digital signatures apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution. Previous experimental demonstrations have been limited to transmission distances of less than 5-km of optical fiber in a laboratory setting. Here we report the first demonstration of quantum digital signatures over installed optical fiber as well as the longest transmission link reported to date. This demonstration used a 90-km long Differential Phase Shift quantum key distribution system to achieve approximately one signed bit per second - an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations.