Enhancing classical simulation with noisy quantum devices

TL;DR

This paper introduces NDE-CS, a hybrid simulation method that leverages noisy quantum hardware to significantly reduce the sampling cost of classical simulations of quantum circuits, turning noise into a computational resource.

Contribution

The paper presents NDE-CS, a novel protocol that uses noisy quantum device data to enhance classical Monte Carlo simulations, enabling more efficient quantum circuit estimation.

Findings

NDE-CS achieves orders-of-magnitude reduction in sampling cost.

NDE-CS maintains accuracy while reducing cost compared to classical methods.

NDE-CS scales more favorably than SPD with system size.

Abstract

As quantum devices continue to improve in scale and precision, a central challenge is how to effectively utilize noisy hardware for meaningful computation. Most existing approaches aim to recover noiseless circuit outputs from noisy ones through error mitigation or correction. Here, we show that noisy quantum devices can be directly leveraged as computational resources to enhance the classical simulation of quantum circuits. We introduce the Noisy-device-enhanced Classical Simulation (NDE-CS) protocol, which improves stabilizer-based classical Monte Carlo simulation methods by incorporating data obtained from noisy quantum hardware. Specifically, NDE-CS uses noisy executions of a target circuit together with noisy Clifford circuits to learn how the target circuit can be expressed in terms of Clifford circuits under realistic noise. The same learned relation can then be reused in the noiseless Clifford limit, enabling accurate estimation of ideal expectation values with substantially reduced sampling cost. Numerical simulations on Trotterized Ising circuits demonstrate that NDE-CS achieves orders-of-magnitude reductions in sampling cost compared to the underlying purely classical Monte Carlo approaches from which it is derived, while maintaining the same accuracy. We also compare NDE-CS with Sparse Pauli Dynamics (SPD), a powerful classical framework capable of simulating quantum circuits at previously inaccessible scales, and provide an example where the cost of SPD scales exponentially with system size, while NDE-CS scales much more favorably. These results establish NDE-CS as a scalable hybrid simulation approach for quantum circuits, where noise can be harnessed as a computational asset.