Scalable General Error Mitigation for Quantum Circuits

TL;DR

This paper presents a scalable error mitigation method for quantum circuits that reduces calibration overhead by making it independent of qubit count, demonstrated on circuits up to 100 qubits.

Contribution

The authors improve the General Error Mitigation method by reducing calibration complexity, enabling scalability to larger quantum circuits.

Findings

Mitigation performs comparably to GEM with fewer calibration runs.

Calibration complexity depends only on output distribution sparsity.

Successful mitigation demonstrated on a 100-qubit circuit.

Abstract

In quantum computing, error mitigation is a method to improve the results of an error-prone quantum processor by post-processing them on a classical computer. In this work, we improve the General Error Mitigation (GEM) method for scalability. GEM relies on the use of a matrix to represent the device error, which requires the execution of $2^{n+1}$ calibration circuits on the quantum hardware, where $n$ is the number of qubits. With our improved method, the number of calibration runs is independent of the number of qubits and depends only on the number of non-zero states in the output distribution. We run 1853 randomly generated circuits with widths between 2-7 qubits and depths between 10-140 gates on IBMQ superconducting devices. The experiments show that the mitigation works comparably well to GEM, while requiring a fraction of the calibration runs. Finally, an experiment to mitigate errors in a 100 qubit circuit demonstrates the scalable features of our method.