Experimental quantum channel discrimination using metastable states of a trapped ion

TL;DR

This paper demonstrates high-accuracy discrimination of three quantum channels using a single trapped ion, leveraging metastable states and protocols analogous to classical communication schemes, with over 99% success rate.

Contribution

It introduces experimental techniques for quantum channel discrimination using metastable ion states, achieving high accuracy and implementing classical communication analogues in quantum systems.

Findings

Discrimination accuracy exceeds 99% for all channels.

Developed techniques for using 6-dimensional ion state space.

Implemented quantum analogues of classical modulation schemes.

Abstract

We present experimental demonstrations of accurate and unambiguous single-shot discrimination between three quantum channels using a single trapped $^{40}\text{Ca}^{+}$ ion. The three channels cannot be distinguished unambiguously using repeated single channel queries, the natural classical analogue. We develop techniques for using the 6-dimensional $\text{D}_{5/2}$ state space for quantum information processing, and we implement protocols to discriminate quantum channel analogues of phase shift keying and amplitude shift keying data encodings used in classical radio communication. The demonstrations achieve discrimination accuracy exceeding $99\%$ in each case, limited entirely by known experimental imperfections.