TY - JOUR

T1 - Improved DIQKD protocols with finite-size analysis

AU - Tan, Ernest Y.Z.

AU - Sekatski, Pavel

AU - Bancal, Jean Daniel

AU - Schwonnek, René

AU - Renner, Renato

AU - Sangouard, Nicolas

AU - Lim, Charles C.W.

N1 - Funding information: E. Y.-Z. T. and R. R. are supported by the Swiss National Science Foundation (SNSF) grant number 20QT21 187724 via the National Center for Competence in Research for Quantum Science and Technology (QSIT), the Air Force Office of Scientific Research (AFOSR) via grant FA9550-19-1-0202, and the QuantERA project eDICT. P. S. is supported by by the Swiss National Science Foundation (SNSF). C. C.-W. L is supported by the National Research Foundation (NRF) Singapore, under its NRF Fellowship programme (NRFF11-2019-0001) and Quantum Engineering Programme 1.0 (QEP-P2).

PY - 2022/12/22

Y1 - 2022/12/22

N2 - 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.

AB - 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.

UR - http://www.scopus.com/inward/record.url?scp=85151414484&partnerID=8YFLogxK

U2 - 10.22331/Q-2022-12-22-880

DO - 10.22331/Q-2022-12-22-880

M3 - Article

AN - SCOPUS:85151414484

VL - 6

JO - Quantum

JF - Quantum

SN - 2521-327X

ER -