Experimental study of multiple-shot unitary channels discrimination using the IBM Q computers

TL;DR

This paper experimentally investigates the discrimination of two quantum unitary channels using IBM Q hardware, revealing that shallow, low-entanglement circuits outperform deeper, highly entangled ones in noisy quantum environments.

Contribution

It provides the first experimental validation of quantum channel discrimination strategies on real quantum hardware, emphasizing the importance of circuit depth and entanglement management.

Findings

Shallow circuits with minimal entanglement perform better under hardware noise.

Deep or highly entangled circuits are less effective for discrimination on noisy devices.

Optimal circuit architectures balance discrimination power and noise resilience.

Abstract

Tasks involving black boxes appear frequently in quantum computer science. An example that has been deeply studied is quantum channel discrimination. In this work, we study the discrimination between two quantum unitary channels in the multiple-shot scenario. We challenge the theoretical results concerning the probability of correct discrimination with the results collected from experiments performed on the IBM Quantum processor Brisbane. Our analysis shows that neither too deep quantum circuits nor circuits that create too much entanglement are suitable for the discrimination task. We conclude that circuit architectures which minimize entanglement overhead while preserving discrimination power are significantly more resilient to hardware noise if their depth does not overpass threshold value.