Simulating dynamic quantum phase transitions in photonic quantum walks

TL;DR

This paper experimentally investigates dynamic quantum phase transitions in photonic quantum walks, demonstrating the simulation of topological phase quenches, characterization of DQPTs and DTOPs, and exploring non-unitary dynamics and mixed states.

Contribution

It presents the first experimental study of DQPTs in photonic quantum walks, including their relation to DTOPs and exploration of non-unitary and mixed state dynamics.

Findings

Confirmed the relation between DQPTs and DTOPs in topological systems.

Demonstrated DQPTs in mixed states and parity-time-symmetric non-unitary dynamics.

Validated quantum walks as a versatile platform for simulating topological phenomena.

Abstract

Signaled by non-analyticities in the time evolution of physical observables, dynamic quantum phase transitions (DQPTs) emerge in quench dynamics of topological systems and possess an interesting geometric origin captured by dynamic topological order parameters (DTOPs). In this work, we report the experimental study of DQPTs using discrete-time quantum walks of single photons. We simulate quench dynamics between distinct Floquet topological phases using quantum-walk dynamics, and experimentally characterize DQPTs and the underlying DTOPs through interference-based measurements. The versatile photonic quantum-walk platform further allows us to experimentally investigate DQPTs for mixed states and in parity-time-symmetric non-unitary dynamics for the first time. Our experiment directly confirms the relation between DQPTs and DTOPs in quench dynamics of a topological system, and opens up the avenue of simulating emergent topological phenomena using discrete-time quantum-walk dynamics.