Investigating the variance increase of readout error mitigation through classical bit-flip correction on IBM and Rigetti quantum computers

TL;DR

This paper evaluates a classical bit-flip correction method for readout error mitigation on IBM and Rigetti quantum computers, showing it improves measurement accuracy with only moderate variance increase.

Contribution

It provides a comparative analysis of the method's performance on different hardware and derives a new variance expression for mitigated measurements.

Findings

Mitigation improves measurement accuracy on IBM and Rigetti devices.

Variance increase due to mitigation is moderate and well-predicted.

Theoretical predictions align with experimental hardware results.

Abstract

Readout errors are among the most dominant errors on current noisy intermediate-scale quantum devices. Recently, an efficient and scaleable method for mitigating such errors has been developed, based on classical bit-flip correction. In this talk, we compare the performance of this method for IBM's and Rigetti's quantum devices, demonstrating how the method improves the noisy measurements of observables obtained on the quantum hardware. Moreover, we examine the variance amplification to the data after applying of our mitigation procedure, which is common to all mitigation strategies. We derive a new expression for the variance of the mitigated Pauli operators in terms of the corrected expectation values and the noisy variances.Our hardware results show good agreement with the theoretical prediction, and we demonstrate that the increase of the variance due to the mitigation procedure is only moderate.