Finite-Size Security for Discrete-Modulated Continuous-Variable Quantum Key Distribution Protocols
Discrete-Modulated (DM) Continuous-Variable Quantum Key Distribution (CV-QKD) protocols are promising candidates for commercial implementations of quantum communication networks due to their experimental simplicity. While tight security analyses in the asymptotic limit exist, proofs in the finite-size regime are still subject to active research. We present a composable finite-size security proof against independently and identically distributed (i.i.d.) collective attacks for a general DM CV-QKD protocol. We introduce a new energy testing theorem to bound the effective dimension of Bob's system and rigorously prove security within Renner's epsilon-security framework. We introduce and build up our security argument on so-called acceptance testing which, as we argue, is the proper notion for the statistical analysis in the finite-size regime and replaces the concept of parameter estimation for asymptotic security analyses. Finally, we extend and apply a numerical security proof technique to calculate tight lower bounds on the secure key rate. To demonstrate our method, we apply it to a quadrature phase-shift keying protocol, both for untrusted, ideal and trusted non-ideal detectors. The results show that our security proof method yields secure finite-size key rates under experimentally viable conditions up to at least 73 km transmission distance.
- Pub Date:
- January 2023
- Quantum Physics
- 28 pages, 6 Figures