Voltage Induced Dynamical Quantum Phase Transitions in Exciton Condensates

TL;DR

This paper investigates voltage-induced quantum phase transitions in exciton condensates within 1D quantum layers, revealing new oscillatory phases and the dynamics of meron flow through a non-perturbative theoretical model.

Contribution

It introduces a novel mapping of exciton condensate physics to a pseudospin ferromagnet model, uncovering additional metastable and paramagnetic phases beyond the known ferromagnetic phase.

Findings

Identification of an oscillatory metastable phase with persistent meron flow

Observation of a transition from coherent to incoherent charge transfer with increasing voltage

Demonstration of voltage quench effects on phase stability and dynamics

Abstract

We explore non-analytic quantum phase dynamics of dipolar exciton condensates formed in a system of 1D quantum layers subjected to voltage quenches. We map the exciton condensate physics on to the pseudospin ferromagnet model showing an additional oscillatory metastable and paramagnetic phase beyond the well-known ferromagnetic phase by utilizing a time-dependent, non-perturbative theoretical model. We explain the coherent phase of the exciton condensate in quantum Hall bilayers, observed for currents equal to and slightly larger than the critical current, as a stable time-dependent phase characterized by persistent charged meron flow in each of the individual layers with a characteristic AC Josephson frequency. As the magnitude of the voltage quench is further increased, we find that the time-dependent current oscillations associated with the charged meron flow decay, resulting in a transient pseudospin paramagnet phase characterized by partially coherent charge transfer between layers, before the state relaxes to incoherent charge transfer between the layers.