Swap Test-based Characterization of Quantum Processes in Universal Quantum Computers

TL;DR

This paper investigates the use of the Swap Test as a non-destructive method to characterize decoherence in quantum processes within universal quantum computers, offering an alternative to full quantum process tomography.

Contribution

It demonstrates that the Swap Test can effectively identify decoherence without destroying the qubit, with specific modifications, providing a practical tool for quantum process characterization.

Findings

Swap Test can identify decoherence in quantum processes

It offers a non-destructive alternative to quantum process tomography

Experimental results support its practical applicability

Abstract

Quantum Computing has been presenting major developments in the last few years, unveiling systems with a increasing number of qubits. However, unreliable quantum processes in universal quantum computers still represent one of the the greatest challenges to be overcome. Such obstacle has its source on noisy operations and interactions with the environment which introduce decoherence to a quantum system. In this article we verify whether a tool called Swap Test is able to identify decoherence. Our experimental results demonstrate that the Swap Test can be employed as an alternative to a full Quantum Process Tomography, with the advantage of not destroying the qubit under test, under certain circumstances, as long as some modifications are introduced.