Distinguishing Unitary Gates on the IBM Quantum Processor

TL;DR

This paper experimentally demonstrates the perfect discrimination of two specific single-qubit unitary gates on IBM's quantum processor using parallel and sequential schemes, achieving success probabilities of at least 85%.

Contribution

First experimental implementation of unitary gate discrimination on a real quantum processor using two different schemes.

Findings

Both schemes achieved at least 85% success probability.

Successful implementation on IBM's 5-qubit superconducting processor.

Validated the effectiveness of discrimination schemes in practical quantum computing.

Abstract

An unknown unitary gates, which is secretly chosen from several known ones, can always be distinguished perfectly. In this paper, we implement such a task on IBM's quantum processor. More precisely, we experimentally demonstrate the discrimination of two qubit unitary gates, the identity gate and the $\frac{2}{3}\pi$-phase shift gate, using two discrimination schemes -- the parallel scheme and the sequential scheme. We program these two schemes on the \emph{ibmqx4}, a $5$-qubit superconducting quantum processor via IBM cloud, with the help of the $QSI$ modules [S. Liu et al.,~arXiv:1710.09500, 2017]. We report that both discrimination schemes achieve success probabilities at least 85%.