Sculpting oscillators with light within a nonlinear quantum fluid

TL;DR

This paper demonstrates direct visualization of oscillating quantum fluids in polariton condensates on a semiconductor chip, revealing their wavefunctions and soliton behavior, with potential for integrated quantum devices.

Contribution

It introduces a method to directly image and control oscillating polariton condensates and their wavefunctions in real space, advancing quantum fluid research.

Findings

Direct imaging of oscillating quantum fluids in polariton condensates.

Observation of non-equilibrium solitons in the condensate wavepackets.

Potential for integrated semiconductor quantum devices.

Abstract

Seeing macroscopic quantum states directly remains an elusive goal. Particles with boson symmetry can condense into such quantum fluids producing rich physical phenomena as well as proven potential for interferometric devices [1-10]. However direct imaging of such quantum states is only fleetingly possible in high-vacuum ultracold atomic condensates, and not in superconductors. Recent condensation of solid state polariton quasiparticles, built from mixing semiconductor excitons with microcavity photons, offers monolithic devices capable of supporting room temperature quantum states [11-14] that exhibit superfluid behaviour [15,16]. Here we use microcavities on a semiconductor chip supporting two-dimensional polariton condensates to directly visualise the formation of a spontaneously oscillating quantum fluid. This system is created on the fly by injecting polaritons at two or more spatially-separated pump spots. Although oscillating at tuneable THz-scale frequencies, a simple optical microscope can be used to directly image their stable archetypal quantum oscillator wavefunctions in real space. The self-repulsion of polaritons provides a solid state quasiparticle that is so nonlinear as to modify its own potential. Interference in time and space reveals the condensate wavepackets arise from non-equilibrium solitons. Control of such polariton condensate wavepackets demonstrates great potential for integrated semiconductor-based condensate devices.