Observation of emergent momentum-time skyrmions in parity-time-symmetric non-unitary quench dynamics

TL;DR

This paper reports the experimental detection of momentum-time skyrmions in PT-symmetric non-unitary quench dynamics using single-photon quantum walks, revealing the interplay of PT symmetry and topology in non-Hermitian systems.

Contribution

It demonstrates the first experimental observation of momentum-time skyrmions in non-unitary PT-symmetric systems through quantum walk simulations.

Findings

Observation of momentum-time skyrmions in PT-symmetric systems

Experimental simulation of non-unitary quench dynamics with quantum walks

Identification of dynamic Chern numbers protecting skyrmions

Abstract

Topology in quench dynamics gives rise to intriguing dynamic topological phenomena, which are intimately connected to the topology of static Hamiltonians yet challenging to probe experimentally. Here we experimentally detect momentum-time skyrmions in parity-time (PT)-symmetric non-unitary quench dynamics, which are protected by dynamic Chern numbers defined for the emergent momentum-time manifold. Specifically, we experimentally simulate non-unitary quench dynamics of PT-symmetric topological systems using single-photon discrete-time quantum walks, and demonstrate emergence of skyrmions by constructing the time-dependent non-Hermitian density matrix via direct measurements in position space. Our work experimentally reveals the interplay of PT symmetry and quench dynamics in inducing emergent topological structures, and highlights the application of discrete-time quantum walks for the study of dynamic topological phenomena.