Spontaneous formation and optical manipulation of extended polariton condensates

TL;DR

This paper demonstrates that long-lived polariton condensates can propagate over macroscopic distances with high spatial coherence, and introduces optical methods to manipulate these extended condensates for quantum applications.

Contribution

It presents the first observation of long-range propagation of polariton condensates in a wire microcavity with enhanced lifetime, enabling new control techniques.

Findings

Polariton condensates propagate over macroscopic distances with >50% coherence.

Extended condensates are controlled by optically induced potentials.

Synchronization and trapping of condensates are achieved through optical manipulation.

Abstract

Cavity exciton-polaritons (polaritons) are bosonic quasi-particles offering a unique solid-state system to investigate interacting condensates. Up to now, disorder induced localization and short lifetimes have prevented the establishment of long range off diagonal order needed for any quantum manipulation of the condensate wavefunction. In this work, using a wire microcavity with polariton lifetimes ten times longer than in all previously existing samples, we show that polariton condensates can propagate over macroscopic distances outside the excitation area, while preserving their spontaneous spatial coherence. An extended condensate wave-function builds-up with a degree of spatial coherence larger than 50% over distances 50 times the polariton De Broglie wavelength. The expansion of the condensate is shown to be governed by the repulsive potential induced by photo-generated excitons within the excitation area. The control of this local potential offers a new and versatile method to manipulate extended polariton condensates. As an illustration, we demonstrate synchronization of extended condensates via controlled tunnel coupling and localization of condensates in a trap with optically controlled dimensions.