Multiqubit noise deconvolution and characterization

TL;DR

This paper introduces a noise deconvolution method for multiqubit quantum channels that can recover noiseless expectation values even with complex, correlated noise, improving efficiency over traditional techniques.

Contribution

It develops a universal noise deconvolution protocol applicable to any invertible noise model, including cases with non-physical inverse maps, and allows noise parameter estimation without full process tomography.

Findings

Quadratic speedup for Pauli noise deconvolution

Applicable to correlated and non-Pauli noise models

Simulation results demonstrate effectiveness

Abstract

We present a noise deconvolution technique for obtaining noiseless expectation values of noisy observables at the output of multiqubit quantum channels. For any number of qubits or in the presence of correlations, our protocol applies to any mathematically invertible noise model, even when its inverse map is not physically implementable, i.e. when it is neither completely-positive nor trace-preserving. For a generic observable affected by Pauli noise it provides a quadratic speedup, always producing a rescaling of its Pauli basis components. We show that it is still possible to achieve the deconvolution while experimentally estimating the noise parameters, whenever these are unknown (bypassing resource-heavy techniques such as quantum process tomography). We provide a simulation, with examples for both Pauli and non-Pauli channels.