Analytical Bounds for Dynamic Multi-Channel Discrimination

TL;DR

This paper derives analytical bounds for dynamic, idler-free quantum channel discrimination protocols using multipartite entangled probes, showing they can approach the performance of entangled protocols in quantum sensing.

Contribution

It introduces new analytical bounds for idler-free dynamic discrimination protocols, demonstrating their potential near the performance of entangled strategies.

Findings

Analytical bounds for average error probability in bosonic Gaussian channels.

Idler-free protocols can nearly match entangled protocols in performance.

Multipartite entangled probes enhance quantum channel discrimination.

Abstract

The ability to precisely discriminate multiple quantum channels is fundamental to achieving quantum enhancements in data-readout, target detection, pattern recognition, and more. Optimal discrimination protocols often rely on entanglement shared between an incident probe and a protected idler-mode. While these protocols can be highly advantageous over classical ones, the storage of idler-modes is extremely challenging in practice. In this work, we investigate idler-free block protocols based on the use of multipartite entangled probe states. In particular, we focus on a class of idler-free protocol which uses non-disjoint distributions of multipartite probe states irradiated over multi-channels, known as dynamic discrimination protocols. We derive new, analytical bounds for the average error probability of such protocols in a bosonic Gaussian channel setting, revealing idler-free strategies that display performance close to idler-assistance for powerful, near-term quantum sensing applications.