TEP Seminar - Michael Fraser

Temporal modulation of microcavity exciton-polariton condensates – a macroscopically coherent, hybrid state of cavity photons and quantum well excitons - can be used to controllably drive condensate dynamics, enabling the study of open-dissipative superfluidity and the formation of topological phases. We have used off-resonant driving by the interference of two GHz frequency-offset, structured lasers to demonstrate both transverse [1] and longitudinal [2] dynamics.
In this presentation, I describe the creation of a one-dimensional optical lattice by the angled interference of two quasi-1D beams which drives the formation of tunable artificial bandstructures for polaritons. By further introducing a frequency offset between the two lasers, the optical lattice becomes dynamical, leading to the formation of two-dimensional Floquet-Bloch bands where time plays the role of a synthetic second dimension. The temporal driving causes the bandstructure to become non-reciprocal and acquire a universal tilt connected to the non-trivial topology of the Floquet–Bloch bands.

Dynamical, incoherent manipulation via pump-induced reservoirs is shown to be a versatile method for driving dynamical states of polariton condensates and holds promise for the engineering of robust non-linear, topological phases of light.

References
[1] Y. dV. I. Redondo et al. ‘Optically Driven Rotation of Exciton–Polariton Condensates’ Nano Letters 23, 4564 (2023)
[2] Y. dV. I. Redondo et al. ‘Non-reciprocal band structures in an exciton–polariton Floquet optical lattice’ Nature Photonics 18, 548–553 (2024)