Locating quantum critical points with shallow quantum circuits

TL;DR

This paper introduces Delta-VQE, a shallow quantum circuit-based method for locating quantum critical points efficiently, reducing resource demands and improving detection sharpness in quantum many-body systems.

Contribution

The paper presents Delta-VQE, a novel variational approach that identifies quantum critical points using minimal quantum resources and shallow circuits, enhancing feasibility on near-term devices.

Findings

Delta-VQE accurately locates critical points in various quantum systems.

The method sharpens critical point signatures with shallower circuits.

Delta-VQE demonstrates practical utility on near-term quantum hardware.

Abstract

Quantum critical point is one key concept for studying many-body physics but its investigation may be resource-demanding even for a quantum computer due to the intrinsic complexity. In this paper, we propose an approach based on variational quantum eigensolver(VQE), dubbed as Delta-VQE, for locating the quantum critical point using only shallow quantum circuits. With Delta-VQE, the critical point can be identified as a most confusing point, quantified as zero difference between two variational energies that use two representative reference states of distinct phases of matter. Remarkably, the signature of a critical point as a minimal point can be sharper while using shallower quantum circuits. We test the algorithm for different quantum systems and demonstrate the usefulness of Delta-VQE. The scheme suggests a new avenue for investigating quantum phases of matter on near-term quantum devices with limited quantum resources.