Randomized benchmarking and process tomography for gate errors in a solid-state qubit

TL;DR

This paper compares different methods for measuring single-qubit gate errors in a superconducting qubit, revealing that decoherence limits gate fidelity and providing a detailed analysis of error sources.

Contribution

It introduces a comprehensive comparison of quantum process tomography and randomized benchmarking for assessing gate errors in solid-state qubits.

Findings

Randomized benchmarking shows a minimum average gate error of 1.1%

Gate fidelity decreases exponentially with the number of gates

Decoherence is identified as the primary limit on gate fidelity

Abstract

We present measurements of single-qubit gate errors for a superconducting qubit. Results from quantum process tomography and randomized benchmarking are compared with gate errors obtained from a double pi pulse experiment. Randomized benchmarking reveals a minimum average gate error of 1.1+/-0.3% and a simple exponential dependence of fidelity on the number of gates. It shows that the limits on gate fidelity are primarily imposed by qubit decoherence, in agreement with theory.