# Emergent prethermalization signatures in out-of-time ordered correlations

## TL;DR

This paper reports on nuclear magnetic resonance experiments that observe prethermalization signatures in out-of-time ordered correlations within a spin chain, revealing emergent conserved quantities and advancing understanding of quantum thermalization.

## Contribution

The study introduces a novel protocol for measuring out-of-time ordered correlations and demonstrates the emergence of prethermalization in a controllable quantum system.

## Key findings

- Emergence of conserved quantities at large magnetic fields.
- Early saturation of correlations indicating prethermalization.
- Validation of Hamiltonian engineering techniques for probing quantum dynamics.

## Abstract

How a many-body quantum system thermalizes --or fails to do so-- under its own interaction is a fundamental yet elusive concept. Here we demonstrate nuclear magnetic resonance observation of the emergence of prethermalization by measuring out-of-time ordered correlations. We exploit Hamiltonian engineering techniques to tune the strength of spin-spin interactions and of a transverse magnetic field in a spin chain system, as well as to invert the Hamiltonian sign to reveal out-of-time ordered correlations. At large fields, we observe an emergent conserved quantity due to prethermalization, which can be revealed by an early saturation of correlations. Our experiment not only demonstrates a new protocol to measure out-of-time ordered correlations, but also provides new insights in the study of quantum thermodynamics.