149 research outputs found
Measurement-device-independent quantum communication with an untrusted source
Measurement-device-independent quantum key distribution (MDI-QKD) can provide
enhanced security, as compared to traditional QKD, and it constitutes an
important framework for a quantum network with an untrusted network server.
Still, a key assumption in MDI-QKD is that the sources are trusted. We propose
here a MDI quantum network with a single untrusted source. We have derived a
complete proof of the unconditional security of MDI-QKD with an untrusted
source. Using simulations, we have considered various real-life imperfections
in its implementation, and the simulation results show that MDI-QKD with an
untrusted source provides a key generation rate that is close to the rate of
initial MDI-QKD in the asymptotic setting. Our work proves the feasibility of
the realization of a quantum network. The network users need only low-cost
modulation devices, and they can share both an expensive detector and a
complicated laser provided by an untrusted network server.Comment: 13 pages, 4 figures. arXiv admin note: the security proof technique
is based on arXiv:0802.2725, arXiv:0905.4225
Experimental study of quantum random number generator based on two independent lasers
Quantum random number generator (QRNG) can produce true randomness by
utilizing the inherent probabilistic nature of quantum mechanics. Recently, the
spontaneous-emission quantum phase noise of the laser has been widely deployed
for QRNG, due to its high rate, low cost and the feasibility of chip-scale
integration. Here, we perform a comprehensive experimental study of phase-noise
based QRNG with two independent lasers, each of which operates in either
continuous-wave (CW) or pulsed mode. We implement QRNGs by operating the two
lasers in three configurations, namely CW+CW, CW+pulsed and pulsed+pulsed, and
demonstrate their tradeoffs, strengths and weaknesses.Comment: 7pages,6figures.It has been accepted by PR
Asymmetric Protocols for Scalable High-Rate Measurement-Device-Independent Quantum Key Distribution Networks
Measurement-device-independent quantum key distribution (MDI-QKD) can
eliminate detector side channels and prevent all attacks on detectors. The
future of MDI-QKD is a quantum network that provides service to many users over
untrusted relay nodes. In a real quantum network, the losses of various
channels are different and users are added and deleted over time. To adapt to
these features, we propose a type of protocols that allow users to
independently choose their optimal intensity settings to compensate for
different channel losses. Such protocol enables a scalable high-rate MDI-QKD
network that can easily be applied for channels of different losses and allows
users to be dynamically added/deleted at any time without affecting the
performance of existing users.Comment: Changed the title to better represent the generality of our method,
and added more discussions on its application to alternative protocols (in
Sec. II, the new Table II, and Appendix E with new Fig. 9). Added more
conceptual explanations in Sec. II on the difference between X and Z bases in
MDI-QKD. Added additional discussions on security of the scheme in Sec. II
and Appendix
Pre-fixed Threshold Real Time Selection Method in Free-space Quantum Key Distribution
Free-space Quantum key distribution (QKD) allows two parties to share a
random key with unconditional security, between ground stations, between mobile
platforms, and even in satellite-ground quantum communications. Atmospheric
turbulence causes fluctuations in transmittance, which further affect the
quantum bit error rate (QBER) and the secure key rate. Previous post-selection
methods to combat atmospheric turbulence require a threshold value determined
after all quantum transmission. In contrast, here we propose a new method where
we pre-determine the optimal threshold value even before quantum transmission.
Therefore, the receiver can discard useless data immediately, thus greatly
reducing data storage requirement and computing resource. Furthermore, our
method can be applied to a variety of protocols, including, for example, not
only single-photon BB84, but also asymptotic and finite-size decoy-state BB84,
which can greatly increase its practicality
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