Experimental validation of the Kibble-Zurek Mechanism on a Digital Quantum Computer

TL;DR

This study experimentally tests the Kibble-Zurek mechanism on a single qubit using IBM quantum computers, validating key assumptions and exploring effects of decoherence and crosstalk on quantum phase transition predictions.

Contribution

First experimental validation of the Kibble-Zurek mechanism on a digital quantum computer, analyzing decoherence and crosstalk impacts on quantum phase transition dynamics.

Findings

Experimental data supports the adiabatic-impulse approximation for a single qubit.

Circuit depth increases lead to decoherence, causing deviations from theoretical predictions.

Crosstalk effects vary with circuit topology and influence KZM validation.

Abstract

The Kibble-Zurek mechanism (KZM) captures the essential physics of nonequilibrium quantum phase transitions with symmetry breaking. KZM predicts a universal scaling power law for the defect density which is fully determined by the system's critical exponents at equilibrium and the quenching rate. We experimentally tested the KZM for the simplest quantum case, a single qubit under the Landau-Zener evolution, on an open access IBM quantum computer (IBM-Q). We find that for this simple one-qubit model, experimental data validates the central KZM assumption of the adiabatic-impulse approximation for a well isolated qubit. Furthermore, we report on extensive IBM-Q experiments on individual qubits embedded in different circuit environments and topologies, separately elucidating the role of crosstalk between qubits and the increasing decoherence effects associated with the quantum circuit depth on the KZM predictions. Our results strongly suggest that increasing circuit depth acts as a decoherence source, producing a rapid deviation of experimental data from theoretical unitary predictions.