Digitized counterdiabatic quantum critical dynamics

TL;DR

This paper demonstrates experimentally that digitized counterdiabatic protocols on superconducting quantum processors can significantly reduce topological defect formation during fast quantum phase transitions, improving quantum simulation and optimization.

Contribution

It provides the first experimental validation of digitized counterdiabatic protocols in reducing defects in quantum critical dynamics on superconducting qubits.

Findings

Defect reduction of up to 48% in fast quenches.

Close match between experimental data and theoretical predictions at short times.

Analytic solution for 1D defect distribution in the fast-quench limit.

Abstract

We experimentally demonstrate that a digitized counterdiabatic quantum protocol reduces the number of topological defects created during a fast quench across a quantum phase transition. To show this, we perform quantum simulations of one- and two-dimensional transverse-field Ising models driven from the paramagnetic to the ferromagnetic phase. We utilize superconducting cloud-based quantum processors with up to 156 qubits. Our data reveal that the digitized counterdiabatic protocol reduces defect formation by up to 48% in the fast-quench regime -- an improvement hard to achieve through digitized quantum annealing under current noise levels. The experimental results closely match theoretical and numerical predictions at short evolution times, before deviating at longer times due to hardware noise. In one dimension, we derive an analytic solution for the defect number distribution in the fast-quench limit. For two-dimensional geometries, where analytical solutions are unknown and numerical simulations are challenging, we use advanced matrix-product-state methods. Our findings indicate a practical way to control the topological defect formation during fast quenches and highlight the utility of counterdiabatic protocols for quantum optimization and quantum simulation in material design on current quantum processors.