Private Communication over a Bosonic Compound Channel

TL;DR

This paper derives a capacity formula for the bosonic compound wiretap channel, quantifying how channel uncertainty impacts secure data transmission rates, bridging the gap between insecure high-performance and secure low-performance systems.

Contribution

It provides the first capacity formula for the bosonic compound wiretap channel, explicitly accounting for channel uncertainty in quantum secure communication.

Findings

Quantifies the rate penalty due to channel uncertainty.

Establishes a capacity formula for the bosonic compound wiretap channel.

Highlights the trade-off between security and performance in quantum communication.

Abstract

It is a common belief that quantum key distribution systems are the one and only information-theoretically secure physical layer security protocol that enables secure data transmission without a need for the legitimate parties to have any channel knowledge. It is also known that this high security profile results in severe rate restrictions for the parties utilizing the quantum key distribution systems. This observation raises the question of whether quantifying the level of ignorance of the legitimate parties with regard to the channel parameters may enable us to navigate the large gray zone between insecure but highly performant systems on the one side and perfectly secure but highly non-performant systems on the other side. Indeed, by proving a capacity formula for the bosonic compound wiretap channel using the binary phase shift keying alphabet, we are able to quantify in this work exactly how channel uncertainty penalizes data transmission rates.