Passive decoy-state quantum key distribution with practical light sources

Journal Article · Mon Feb 15 04:00:00 EST 2010 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.81.022310· OSTI ID:21408201

Curty, Marcos ^[1]; Ma, Xiongfeng ^[2]; Qi, Bing ^[3]; Moroder, Tobias ^[2]

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1. ETSI Telecomunicacion, Department of Signal Theory and Communications, University of Vigo, Campus Universitario, E-36310 Vigo (Pontevedra) (Spain)
2. Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, N2L 3G1 Waterloo, Ontario (Canada)
3. Center for Quantum Information and Quantum Control, Department of Physics and Department of Electrical and Computer Engineering, University of Toronto, M5S 3G4 Toronto, Ontario (Canada)

Decoy states have been proven to be a very useful method for significantly enhancing the performance of quantum key distribution systems with practical light sources. Although active modulation of the intensity of the laser pulses is an effective way of preparing decoy states in principle, in practice passive preparation might be desirable in some scenarios. Typical passive schemes involve parametric down-conversion. More recently, it has been shown that phase-randomized weak coherent pulses (WCP) can also be used for the same purpose [M. Curty et al., Opt. Lett. 34, 3238 (2009).] This proposal requires only linear optics together with a simple threshold photon detector, which shows the practical feasibility of the method. Most importantly, the resulting secret key rate is comparable to the one delivered by an active decoy-state setup with an infinite number of decoy settings. In this article we extend these results, now showing specifically the analysis for other practical scenarios with different light sources and photodetectors. In particular, we consider sources emitting thermal states, phase-randomized WCP, and strong coherent light in combination with several types of photodetectors, like, for instance, threshold photon detectors, photon number resolving detectors, and classical photodetectors. Our analysis includes as well the effect that detection inefficiencies and noise in the form of dark counts shown by current threshold detectors might have on the final secret key rate. Moreover, we provide estimations on the effects that statistical fluctuations due to a finite data size can have in practical implementations.

• OSTI ID: 21408201
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 2 Vol. 81; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
BOSONS
DISTRIBUTION
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
FLUCTUATIONS
LASERS
MASSLESS PARTICLES
MEASURING INSTRUMENTS
MODULATION
NEUTRON DETECTORS
NOISE
OPTICS
PERFORMANCE
PHOTODETECTORS
PHOTONS
PULSES
RADIATION DETECTORS
RADIATIONS
THRESHOLD DETECTORS
VARIATIONS
VISIBLE RADIATION