Composably secure time-frequency quantum key distribution

Abstract

We present a composable security proof, valid against arbitrary attacks and including finite-size effects, for a high dimensional time-frequency quantum key distribution (TFQKD) protocol based upon spectrally entangled photons. Previous works have focused on TFQKD schemes as they combines the impressive loss tolerance of single-photon QKD with the large alphabets of continuous variable (CV) schemes, which enable the potential for more than one bit of secret key per transmission. However, the finite-size security of such schemes has only been proven under the assumption of collective Gaussian attacks. Here, by combining recent advances in entropic uncertainty relations for CVQKD with decoy state analysis, we derive a composable security proof that predicts key rates on the order of Mbits/s over metropolitan distances (40km or less) and maximum transmission distances of up to 140km.

Time-energy uncertainty relation for noisy quantum metrology

“…Entropic uncertainty relations play a central role in quantum cryptography [11,15,16,90], and cryptographic schemes have been studied for quantum metrology [91]. It is possible that our parameter estimation trade-off can similarly form the basis of cryptographic schemes in which a parameter encoded in a quantum state is to be shielded from a malevolent eavesdropper.…”