Improved DIQKD protocols with finite-size analysis

authored by
Ernest Y.Z. Tan, Pavel Sekatski, Jean Daniel Bancal, René Schwonnek, Renato Renner, Nicolas Sangouard, Charles C.W. Lim

The security of finite-length keys is essential for the implementation of device-independent quantum key distribution (DIQKD). Presently, there are several finite-size DIQKD security proofs, but they are mostly focused on standard DIQKD protocols and do not directly apply to the recent improved DIQKD protocols based on noisy preprocessing, random key measurements, and modified CHSH inequalities. Here, we provide a general finite-size security proof that can simultaneously encompass these approaches, using tighter finite-size bounds than previous analyses. In doing so, we develop a method to compute tight lower bounds on the asymptotic keyrate for any such DIQKD protocol with binary inputs and outputs. With this, we show that positive asymptotic keyrates are achievable up to depolarizing noise values of 9.33%, exceeding all previously known noise thresholds. We also develop a modification to random-key-measurement protocols, using a pre-shared seed followed by a “seed recovery” step, which yields substantially higher net key generation rates by essentially removing the sifting factor. Some of our results may also improve the keyrates of device-independent randomness expansion.

External Organisation(s)
ETH Zurich
University of Basel
University of Geneva
Université Paris-Saclay
University of Siegen
National University of Singapore
Publication date
Publication status
Peer reviewed
ASJC Scopus subject areas
Atomic and Molecular Physics, and Optics, Physics and Astronomy (miscellaneous)
Electronic version(s) (Access: Open)