Benchmarking universal quantum gates via channel spectrum

TL;DR

The paper introduces channel spectrum benchmarking (CSB), a scalable, error-insensitive method to directly infer noise properties of quantum gates from their channel eigenvalues, applicable to universal gates and complex circuits.

Contribution

It presents CSB, a novel benchmarking technique that overcomes limitations of existing methods by providing direct noise metrics for individual gates and circuit modules.

Findings

CSB accurately estimates process fidelity and stochastic fidelity.

It is insensitive to state-preparation and measurement errors.

CSB is scalable to many-qubit systems and applicable to universal gates.

Abstract

Noise remains the major obstacle to scalable quantum computation. Quantum benchmarking provides key information on noise properties and is an important step for developing more advanced quantum processors. However, current benchmarking methods are either limited to a specific subset of quantum gates or cannot directly describe the performance of the individual target gate. To overcome these limitations, we propose channel spectrum benchmarking (CSB), a method to infer the noise properties of the target gate, including process fidelity, stochastic fidelity, and some unitary parameters, from the eigenvalues of its noisy channel. Our CSB method is insensitive to state-preparation and measurement errors, and importantly, can benchmark universal gates and is scalable to many-qubit systems. Unlike standard randomized schemes, CSB can provide direct noise information for both target native gates and circuit fragments, allowing benchmarking and calibration of global entangling gates and frequently used modules in quantum algorithms like Trotterized Hamiltonian evolution operator in quantum simulation.