Super-resolution of Green's functions on noisy quantum computers

TL;DR

This paper demonstrates that Atomic Norm Minimization can significantly improve the resolution of Green's functions on noisy quantum computers, enabling more accurate spectral reconstructions with shallower circuits.

Contribution

It introduces the application of super-resolution techniques, specifically Atomic Norm Minimization, to quantum spectral function reconstruction on near-term quantum hardware.

Findings

Atomic Norm Minimization reduces circuit depth needed for accurate spectrum recovery.

Reconstruction error is an order of magnitude smaller than standard methods.

Super-resolution can enable simulation of larger quantum systems on noisy hardware.

Abstract

Quantum computers, using efficient Hamiltonian evolution routines, have the potential to simulate Green's functions of classically-intractable quantum systems. However, the decoherence errors of near-term quantum processors prohibit large evolution times, posing limits to the spectrum resolution. In this work, we show that Atomic Norm Minimization, a well-known super-resolution technique, can significantly reduce the minimum circuit depth for accurate spectrum reconstruction. We demonstrate this technique by recovering the spectral function of an impurity model from measurements of its Green's function on an IBM quantum computer. The reconstruction error with the Atomic Norm Minimization is one order of magnitude smaller than with more standard signal processing methods. Super-resolution methods can facilitate the simulation of large and previously unexplored quantum systems, and may constitute a useful non-variational tool to establish a quantum advantage in a nearer future.