865 research outputs found
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
Draw-down Parisian ruin for spectrally negative L\'{e}vy process
In this paper we study the draw-down related Parisian ruin problem for
spectrally negative L\'{e}vy risk processes. We introduce the draw-down
Parisian ruin time and solve the corresponding two-sided exit time via
excursion theory. We also obtain an expression of the potential measure for the
process killed at the draw-down Parisian time. As applications, new results are
obtained for spectrally negative L\'{e}vy risk process with dividend barrier
and Parisian ruin
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