Continuous-variable quantum key distribution in fast fading channels

TL;DR

This paper evaluates the robustness of continuous-variable quantum key distribution protocols in fast fading channels affected by atmospheric turbulence, demonstrating their ability to maintain high key rates even under worst-case eavesdropper control.

Contribution

It analyzes the performance of various CV-QKD protocols in fast fading channels with eavesdropper control, highlighting their resilience and potential for secure quantum communication.

Findings

Protocols achieve high key rates despite eavesdropper control

Fading channels do not significantly compromise protocol security

Various configurations of CV-QKD remain effective in turbulent conditions

Abstract

We investigate the performance of several continuous-variable quantum key distribution protocols in the presence of fading channels. These are lossy channels whose transmissivity changes according to a probability distribution. This is typical in communication scenarios where remote parties are connected by free-space links subject to atmospheric turbulence. In this work, we assume the worst-case scenario where an eavesdropper has full control of a fast fading process, so that she chooses the instantaneous transmissivity of a channel, while the remote parties can only detect the mean statistical process. In our study, we consider coherent-state protocols run in various configurations, including the one-way switching protocol in reverse reconciliation, the measurement-device-independent protocol in the symmetric configuration and a three-party measurement-device-independent network. We show that, regardless of the advantage given to the eavesdropper (full control of fading), these protocols can still achieve high rates.