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.
Highlights
Besides being a beautiful idea, device-independent quantum key distribution (DIQKD) is probably the ultimate solution to defeat quantum hacking
Motivated by the results of the previous subsection, we focus on the entanglement swapping relay (ESR) architecture for the qubit amplifier at Bob’s lab, and we consider entanglement bipartite entangled states written as sources ρab and ρbc (as in that generate a coherent superposition of ψ ab = p0 φ0 ab + p1 φ1 ab + p2 φ2 ab, (11)
Device independence is a desirable feature for quantum key distribution (QKD) to defeat quantum hacking
Summary
Besides being a beautiful idea, device-independent quantum key distribution (DIQKD) is probably the ultimate solution to defeat quantum hacking. Intense theoretical and experimental research[3,4,5] has turned this latter task—called quantum key distribution (QKD)—into a feasible commercial solution[6] Despite such tremendous progress, a major flaw of QKD today is the existing big gap between the theory and the practice. Given that the users’ devices are honest[20,21], DIQKD can guarantee security without characterizing the internal functioning of the apparatuses, thereby ruling out all hacking attacks against the physical implementation It is based on a feature of some entangled states known as nonlocality[22], which guarantees that two distant parties (say, Alice and Bob) sharing an ideal nonlocal quantum state observe perfectly correlated outcomes when performing adequate quantum measurements on their shares. The security proof in[28] relies on the so-called entropy accumulation theorem[30,31], which effectively allows to prove the security of the full protocol from the security of a single round of the protocol by using a worst-case scenario
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