Secret key capacity of the thermal-loss channel: Improving the lower bound

TL;DR

This paper advances understanding of the secret key capacity of the thermal-loss channel by improving the lower bound through the use of Gaussian protocols with trusted-noise detectors, aiding quantum communication security.

Contribution

It introduces a new method to enhance the lower bound of secret key capacity using Gaussian protocols with trusted-noise detectors, surpassing previous bounds.

Findings

Improved lower bound on secret key capacity of the thermal-loss channel.

Demonstrated effectiveness of Gaussian protocols with trusted-noise detectors.

Provides tighter bounds for quantum key distribution security analysis.

Abstract

We consider the secret key capacity of the thermal loss channel, which is modeled by a beam splitter mixing an input signal mode with an environmental thermal mode. This capacity is the maximum value of secret bits that two remote parties can generate by means of the most general adaptive protocols assisted by unlimited and two-way classical communication. To date, only upper and lower bounds are known. The present work improves the lower bound by resorting to Gaussian protocols based on suitable trusted-noise detectors.