Advances in quantum cryptography

TLDR

Quantum cryptography is the fastest growing area in quantum information science, with new protocols, improving security proofs, and a gradual shift from laboratory demonstrations to field prototypes. This review aims to introduce and survey recent theoretical and experimental advances in quantum cryptography, including limits, repeaters, and extensions beyond standard QKD. The authors review discrete‑variable QKD protocols, device independence, satellite and high‑rate continuous‑variable schemes, and future directions such as quantum repeaters, networks, data locking, and digital signatures.

Abstract

Quantum cryptography is arguably the fastest growing area in quantum information science. Novel theoretical protocols are designed on a regular basis, security proofs are constantly improving, and experiments are gradually moving from proof-of-principle lab demonstrations to in-field implementations and technological prototypes. In this review, we provide both a general introduction and a state of the art description of the recent advances in the field, both theoretically and experimentally. We start by reviewing protocolsof quantum key distribution based on discrete variable systems. Next we consider aspects of device independence, satellite challenges, and high rate protocols based on continuous variable systems. We will then discuss the ultimate limits of point-to-point private communications and how quantum repeaters and networks may overcome these restrictions. Finally, we will discuss some aspects of quantum cryptography beyond standard quantum key distribution, including quantum data locking and quantum digital signatures.