Correcting Coherent Errors by Random Operation on Actual Quantum Hardware

TL;DR

This paper investigates the impact of various noise mechanisms in quantum hardware, highlighting the dominance of coherent errors, and demonstrates a method to mitigate these errors by inserting random unitaries, thereby improving quantum computation reliability.

Contribution

It introduces a practical approach to correct coherent errors in quantum circuits using random unitaries, based on full process tomography and echo experiments on real hardware.

Findings

Coherent errors are the dominant noise source in current quantum devices.

Inserting random unitaries significantly extends reliable quantum circuit length.

The method improves the fidelity of quantum computations on noisy hardware.

Abstract

Characterizing and mitigating errors in current noisy intermediate-scale devices is important to improve performance of next generations of quantum hardware. In order to investigate the importance of the different noise mechanisms affecting quantum computation, we perform full quantum process tomography of single qubits in a real quantum processor in which echo experiments are implemented. Besides error sources already included in standard models, the obtained results show the dominant role of coherent errors, which we practically correct by inserting random single-qubit unitaries in the quantum circuit, significantly increasing the circuit length over which quantum computations on actual quantum hardware produce reliable results.