Bridging the gap between theory and practice in quantum cryptography

Quantum key distribution (QKD) needs to close the big gap between theory and practice to be a suitable technology for achieving information-theoretic secure communications. Indeed, recent studies on side-channel attacks have exposed the vulnerabilities of QKD implementations against an eavesdropper who may try to attack both the source and the measurement device. Here, we review two potential approaches that, combined, could bring this goal closer: measurement-device-independent QKD and the loss-tolerant QKD protocol. The former removes all possible side-channels from the measurement apparatus and guarantees a high performance over long distances. The latter appears as a robust solution against typical source flaws and it offers similar key rates as those of standard QKD systems. Most importantly, the feasibility of both solutions has already been demonstrated in several lab and field-test experiments.