Passive Decoy-State Quantum Key Distribution with Coherent Light

Abstract

Signal state preparation in quantum key distribution schemes can be realized using either an active or a passive source. Passive sources might be valuable in some scenarios; for instance, in those experimental setups operating at high transmission rates, since no externally driven element is required. Typical passive transmitters involve parametric down-conversion. More recently, it has been shown that phase-randomized coherent pulses also allow passive generation of decoy states and Bennett-Brassard 1984 (BB84) polarization signals, though the combination of both setups in a single passive source is cumbersome. In this paper, we present a complete passive transmitter that prepares decoy-state BB84 signals using coherent light. Our method employs sum-frequency generation together with linear optical components and classical photodetectors. In the asymptotic limit of an infinite long experiment, the resulting secret key rate (per pulse) is comparable to the one delivered by an active decoy-state BB84 setup with an infinite number of decoy settings.

Fully passive entanglement based quantum key distribution scheme

“…This can be advantageous for example when deploying QKD system on a satellite. Many groups have proposed schemes to implement passive decoy state QKD systems based on parametric down conversion (PDC) [12][13][14][15][16][17][18][19] as well as on WCP [11,[20][21][22][23][24] and both types of sources have recently already been implemented [25][26][27][28][29][30]. Another scheme for passive QKD, which does not rely on the generation of decoy states, is based on entanglement and has been implemented in a wide range of systems with the most prominent utilizing the polarization or the time degree of freedom [31][32][33][34][35][36][37][38][39][40][41][42][43][44][45].…”

Passive state preparation in the Gaussian-modulated coherent-states quantum key distribution

“…As the transmission rate in QKD has been growing dramatically over the years, it is becoming more and more challenging to prepare quantum state precisely at the corresponding speed. More recently, passive state preparation schemes have been proposed in QKD as an alternative approach [13][14][15][16][17][18][19][20][21][22][23][24][25]. In this scheme, Alice explores intrinsic fluctuations of the source, or intentionally designs the source in a way such that certain parameters (for example, intensity) will present unpredictable fluctuations.…”

“…This idea was initially proposed as a simple way to generate random intensity fluctuations in the decoy-state QKD protocols [13][14][15]. Later on, it was also applied in preparing the four BB84 states approximately [24].…”

“…More recently, passive state preparation schemes have been proposed in QKD as an alternative approach [13][14][15][16][17][18][19][20][21][22][23][24][25]. In this scheme, Alice explores intrinsic fluctuations of the source, or intentionally designs the source in a way such that certain parameters (for example, intensity) will present unpredictable fluctuations.…”

Quantum Cryptography for Nuclear Command and Control

“…(Usekno, et al, 2016)). Jacobsen, et al, proposed loosening the requirement for shot-noise limited operation in existing experimental implementations of continuous-variable quantum key distribution, which permits the cheaper laser sources, and potentially integrated systems (Jacobsen, et al, 2015. Further developments in quantum key distribution with coherent light were studied by Curty, et al (Curty, et al, 2015). Shaari, et al, introduced a security proof for two-way quantum key distribution protocols, against the most general eavesdropping attack, that utilize an entropic uncertainty relation (Shaari, et al, 2015).…”