Increasing the Measured Effective Quantum Volume with Zero Noise Extrapolation

TL;DR

This paper demonstrates that Zero-Noise Extrapolation combined with dynamical decoupling can increase the effective quantum volume of IBM quantum processors beyond their vendor-measured values, showcasing improved error mitigation techniques.

Contribution

It introduces a method combining ZNE and dynamical decoupling to enhance effective quantum volume, surpassing traditional measurements.

Findings

Effective quantum volume exceeds vendor-measured values on four IBM devices.

ZNE with circuit folding and dynamical decoupling improves error mitigation.

First reported increase in effective quantum volume using these techniques.

Abstract

Quantum Volume is a full-stack benchmark for near-term quantum computers. It quantifies the largest size of a square circuit which can be executed on the target device with reasonable fidelity. Error mitigation is a set of techniques intended to remove the effects of noise present in the computation of noisy quantum computers when computing an expectation value of interest. Effective quantum volume is a proposed metric that applies error mitigation to the quantum volume protocol in order to evaluate the effectiveness not only of the target device but also of the error mitigation algorithm. Digital Zero-Noise Extrapolation (ZNE) is an error mitigation technique that estimates the noiseless expectation value using circuit folding to amplify errors by known scale factors and extrapolating to the zero-noise limit. Here we demonstrate that ZNE, with global and local unitary folding with fractional scale factors, in conjunction with dynamical decoupling, can increase the effective quantum volume over the vendor-measured quantum volume. Specifically, we measure the effective quantum volume of four IBM Quantum superconducting processor units, obtaining values that are larger than the vendor-measured quantum volume on each device. This is the first such increase reported.