Experimentally verifying anti-Kibble-Zurek behavior in a quantum system under noisy control field

TL;DR

This paper experimentally demonstrates anti-Kibble-Zurek behavior in a quantum system with noisy control, showing that slower driving can increase defects, and establishes a universal power law for optimal quench time relative to noise.

Contribution

It provides the first experimental verification of anti-KZ behavior in quantum systems under noisy control fields using trapped ions.

Findings

Anti-KZ behavior observed in three quantum phase transition protocols.

Optimal quench time scales as a universal power law with noise intensity.

Highlights limitations of adiabatic protocols like quantum annealing.

Abstract

Kibble-Zurek mechanism (KZM) is a universal framework which could in principle describe phase transition phenomenon in any system with required symmetry properties. However, a conflicting observation termed anti-KZ behavior has been reported in the study of ferroelectric phase transition, in which slower driving results in more topological defects [S. M. Griffin, et al. Phys. Rev. X. 2, 041022 (2012)]. Although this research is significant, its experimental simulations have been scarce until now. In this work, we experimentally demonstrate anti-KZ behavior under noisy control field in three kinds of quantum phase transition protocols using a single trapped Yb ion. The density of defects is studied as a function of the quench time and the noise intensity. We experimentally verify that the optimal quench time to minimize excitation scales as a universal power law of the noise intensity. Our research sets a stage for quantum simulation of such anti-KZ behavior in two-level systems and reveals the limitations of the adiabatic protocols such as quantum annealing.