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

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.

Main text: 17 pages, 6 figures. Supplementary Material: 4 pages. Version 3: Published version

References in corpus (8)

• Supplementary information for "Quantum supremacy using a programmable superconducting processor"
• QuTiP 2: A Python framework for the dynamics of open quantum systems
• Quantum computational advantage using photons
• Direct Fidelity Estimation from Few Pauli Measurements
• Defect production in non-linear quench across a quantum critical point
• Optimal non-linear passage through a quantum critical point
• Dynamics of a quantum phase transition in a ferromagnetic Bose-Einstein condensate
• Experimental verification of fluctuation relations with a quantum computer