Towards a realization of device-independent quantum key distribution

Abstract

In the implementation of device-independent quantum key distribution we are interested in maximizing the key rate, i.e. the number of key bits that can be obtained per signal, for a fixed security parameter. In the finite size regime, we furthermore also care about the minimum number of signals required before key can be obtained at all. Here, we perform a fully finite size analysis of device independent protocols using the CHSH inequality both for collective and coherent attacks. For coherent attacks, we sharpen the results recently derived in Arnon-Friedman et al., Nat. Commun. 9, 459 (2018) [1], to reduce the minimum number of signals before key can be obtained. In the regime of collective attacks, where the devices are restricted to have no memory, we employ two different techniques that exploit this restriction to further reduce the number of signals. We then discuss experimental platforms in which DIQKD may be implemented. We analyse Bell violations and expected QBER achieved in previous Bell tests with distant setups and situate these parameters in the security analysis. Moreover, focusing on one of the experimental platforms, namely nitrogen-vacancy based systems, we describe experimental improvements that can lead to a device-independent quantum key distribution implementation in the near future. arXiv:1811.07983v2 [quant-ph]

Advantage Distillation for Device-Independent Quantum Key Distribution

“…Tighter bounds on F (ρ E|00 , ρ E|11 ) should give similar results in DIQKD, hence this would be an important next step. Alternatively, one could analyse the finite-key security [3,39,40]. Since our approach yields explicit bounds [21] on the entropies in Eq.…”

“…Since our approach yields explicit bounds [21] on the entropies in Eq. (1), it could in principle be extended to a finite-size security proof against collective attacks by using the quantum asymptotic equipartition property [41], following the approach in [40]. However, this approach is likely to require a large number of rounds to achieve positive key rates, which would pose a challenge for practical implementation.…”

Device-independent quantum key distribution with random key basis

“…high Bell violation and low bit error rate), which in practice requires ultra-low-noise setups with very high detection efficiencies; though in recent years the gap between the theory and practice has been significantly reduced owing to more powerful proof techniques 9 , 10 , 13 and the demonstrations of loophole-free Bell experiments 14 – 17 . The present gap is best illustrated by Murta et al 18 , whose feasibility study showed that current loophole-free Bell experiments are just short of generating positive key rates assuming the original DIQKD protocol 2 , 3 (see the dashed line in Fig. 3 ).…”

Device-independent quantum key distribution with asymmetric CHSH inequalities

“…A second motivation is more practical. Demonstrating a working and secure device-independent protocol remains technologically highly challenging [16,17] as it requires entangled particles to be distributed and detected with low noise and a high detection rate over long distances. Our results lead to two refinements to the CHSH-based protocol that ease these demands.…”