A model for optimizing quantum key distribution with continuous-wave pumped entangled-photon sources

TL;DR

This paper introduces a new, accurate model for optimizing entanglement-based quantum key distribution systems with continuous-wave lasers, enabling better performance and understanding of fundamental limits.

Contribution

It provides the first detailed model for entanglement-based QKD with continuous-wave pumps, allowing optimization of source brightness and system parameters.

Findings

Model accurately predicts optimal trade-offs for secure key rates.

Validation against experimental data confirms model reliability.

Enables improved design and analysis of QKD systems.

Abstract

Quantum Key Distribution (QKD) allows unconditionally secure communication based on the laws of quantum mechanics rather then assumptions about computational hardness. Optimizing the operation parameters of a given QKD implementation is indispensable in order to achieve high secure key rates. So far, there exists no model that accurately describes entanglement-based QKD with continuous-wave pump lasers. For the first time, we analyze the underlying mechanisms for QKD with temporally uniform pair-creation probabilities and develop a simple but accurate model to calculate optimal trade-offs for maximal secure key rates. In particular, we find an optimization strategy of the source brightness for given losses and detection-time resolution. All experimental parameters utilized by the model can be inferred directly in standard QKD implementations, and no additional assessment of device performance is required. Comparison with experimental data shows the validity of our model. Our results yield a tool to determine optimal operation parameters for already existing QKD systems, to plan a full QKD implementation from scratch, and to determine fundamental key rate and distance limits of given connections.