Topological Unwinding in an Exciton-Polariton Condensate Array

TL;DR

This paper demonstrates that in a nonlinear exciton-polariton condensate array, collective phase unwinding from a π- to zero-state occurs due to the interplay of nonlinearity and topological defects, revealing new dynamics beyond linear protection.

Contribution

It provides the first experimental evidence and theoretical explanation of collective phase unwinding caused by topological defects in a nonlinear polaritonic system.

Findings

Spontaneous phase unwinding observed from π- to zero-state.

Unwinding driven by nonlinearity and topological defects.

Reanalysis supports collective mode transition over single-particle competition.

Abstract

The phase distribution in a Bose-Einstein condensate can realize various topological states classified by distinct winding numbers. While states with different winding numbers are topologically protected in the linear Schr\"odinger equation, when nonlinearities are introduced, violations of the topological protection can occur, leading to unwinding. Exciton-polariton condensates constitute a nonlinear open-dissipative system that is well suited to studying such physics. Here we show that a one-dimensional array of exciton-polariton condensates displays a spontaneous phase unwinding from a $\pi$- to zero-state. We clarify that this collective mode transition is caused by the combined effect of nonlinearity and topological defects in the condensates. While the mode-switching phenomenon observed in our previous experiment was interpreted as the single-particle mode competition, we offer an alternative explanation in terms the collective phase unwinding and find its evidence by reanalyzing the experimental data. Our results open a route towards active control of the mode switching by manipulating the topological defects in prospective quantum polaritonic devices.