Long-distance device-independent quantum key distribution

Abstract

Besides being a beautiful idea, device-independent quantum key distribution (DIQKD) is probably the ultimate solution to defeat quantum hacking. Its security is based on a loophole-free violation of a Bell inequality, which results in a very limited maximum achievable distance. To overcome this limitation, DIQKD must be furnished with heralding devices like, for instance, qubit amplifiers, which can signal the arrival of a photon before the measurement settings are actually selected. In this way, one can decouple channel loss from the selection of the measurement settings and, consequently, it is possible to safely post-select the heralded events and discard the rest, which results in a significant enhancement of the achievable distance. In this work, we investigate photonic-based DIQKD assisted by two main types of qubit amplifiers in the finite data block size scenario, and study the resources—particularly, the detection efficiency of the photodetectors and the quality of the entanglement sources—that would be necessary to achieve long-distance DIQKD within a reasonable time frame of signal transmission.

Measurement-device-independent quantum key distribution with leaky sources

“…The security of DI-QKD relies on the violation of a Bell inequality 9,10 and no knowledge about the inner working of the quantum apparatuses is needed given that the apparatuses are 'honest' 11 , i.e., given that they follow the prescriptions of the protocol and not those of Eve. DI-QKD is, however, difficult to implement experimentally with current technology, especially for long distances [12][13][14] . On the other hand, thanks to its feasibility, MDI-QKD has attracted great attention and has been widely experimentally demonstrated in recent years [15][16][17][18][19][20][21][22] .…”

Device-independent quantum key distribution with single-photon sources

“…Note Added. After making this work publically available online at arXiv:1803.07089 [quant-ph], an alike study of CH and SH schemes for DIQKD has been released [72], which by focusing on the Bell violation of the CHSH inequality arrives at slightly higher requirements for local efficiencies but goes beyond the asymptotic key-rate analysis-see also a very recent work [73] that develops finite-key analysis for DIQKD. Moreover, the model of the CH scheme has been developed and explicitly verified against an experimental implementation within the scenario in which Alice and Bob possess an SPDC source of entangled photons each (rather than two single-photon sources) [74].…”

Device-independent quantum secure direct communication against collective attacks

“…Especially, in some standard QKD protocols, the security against collective attacks implies the security against the most general type of attacks [64,65]. Recently, researchers have developed measurement-device-independent QKD [66,67] and DI-QKD protocols [36,37] against coherent attacks. For investigating the full security proof of DI-QSDC, we will try to research on the DI-QSDC against coherent attacks in our later work.…”

“…If we relax this assumption to the device-independent scenario, where Alice's and Bob's measurements are extended to act on a highdimensional space, the security of BB84 protocol is no longer guaranteed [30][31][32][33][34]. In 2007, Acín et al [33] firstly proposed the deviceindependent quantum key distribution (DI-QKD) protocol, which represents a relaxation of the additional assumptions made in traditional QKD protocols [33][34][35][36][37]. It only requires that quantum physics is correct and Alice and Bob do not allow any unwanted signal to escape from their laboratories.…”

“…The noiseless linear amplification (NLA) is an efficient method to solve the transmission photon loss problem [40][41][42][43][44][45][46][47]. Especially, some NLA protocols have been adopted in the DI-QKD protocols [37,[44][45][46]. The entanglement purification protocols (EPPs) can distill the high quality entanglement from low quality entanglement ensembles, and are usually adopted to resist the decoherence [48][49][50][51].…”