Detecting out-of-time-order correlations via quasi-adiabatic echoes as a tool to reveal quantum coherence in equilibrium quantum phase transitions

TL;DR

This paper introduces a novel dynamical approach using out-of-time-order correlations to detect quantum phase transitions and coherence, applicable in experiments where time-reversal is unfeasible.

Contribution

It develops a robust protocol to measure OTOCs via quasi-adiabatic quenches, linking quantum coherence with phase transitions in accessible experimental setups.

Findings

Abrupt changes in coherence and entanglement across phase transitions are observable in MQC spectra.

The proposed method does not require time-reversal, broadening experimental applicability.

OTOCs serve as effective indicators of quantum criticality in studied models.

Abstract

We propose a new dynamical method to connect equilibrium quantum phase transitions and quantum coherence using out-of-time-order correlations (OTOCs). Adopting the iconic Lipkin-Meshkov-Glick and transverse-field Ising models as illustrative examples, we show that an abrupt change in coherence and entanglement of the ground state across a quantum phase transition is observable in the spectrum of multiple quantum coherence (MQC) intensities, which are a special type of OTOC. We also develop a robust protocol to obtain the relevant OTOCs using quasi-adiabatic quenches through the ground state phase diagram. Our scheme allows for the detection of OTOCs without time-reversal of coherent dynamics, making it applicable and important for a broad range of current experiments where time-reversal cannot be achieved by inverting the sign of the underlying Hamiltonian.