# Experimentally testing quantum critical dynamics beyond the Kibble-Zurek mechanism

## TL;DR

This paper experimentally investigates the distribution of topological defects in a quantum phase transition, demonstrating universal scaling beyond the traditional Kibble-Zurek mechanism using a trapped ion quantum simulator.

## Contribution

It extends the understanding of critical dynamics by experimentally verifying the full distribution of defects and their universal scaling laws beyond the mean, incorporating noise effects.

## Key findings

- Kink pair distribution follows a Poisson binomial distribution.
- Universal power-law scaling of cumulants with quench time.
- Deviations due to noise-induced dephasing observed.

## Abstract

We experimentally probe the distribution of kink pairs resulting from driving a one-dimensional quantum Ising chain through the paramagnet-ferromagnet quantum phase transition, using a single trapped ion as a quantum simulator in momentum space. The number of kink pairs after the transition follows a Poisson binomial distribution, in which all cumulants scale with a universal power-law as a function of the quench time in which the transition is crossed. We experimentally verified this scaling for the first cumulants and report deviations due to noise-induced dephasing of the trapped ion. Our results establish that the universal character of the critical dynamics can be extended beyond the paradigmatic Kibble-Zurek mechanism, which accounts for the mean kink number, to characterize the full probability distribution of topological defects.