The Private Classical Capacity of a Partially Degradable Quantum Channel

TL;DR

This paper demonstrates that the private classical capacity of partially degradable quantum channels equals their quantum capacity, simplifies to a single-letter formula, and allows higher private communication rates than standard degradable channels.

Contribution

It proves the equality and single-letterization of private classical capacity for arbitrary dimensional PD channels, extending understanding of quantum communication limits.

Findings

Private classical capacity equals quantum capacity for PD channels

Capacity single-letterizes for PD channels

Higher private communication rates achievable over PD channels

Abstract

For a partially degradable (PD) channel, the channel output state can be used to simulate the degraded environment state. The quantum capacity of a PD channel has been proven to be additive. Here, we show that the private classical capacity of arbitrary dimensional PD channels is equal to the quantum capacity of the channel and also single-letterizes. We prove that higher rates of private classical communication can be achieved over a PD channel in comparison to standard degradable channels.