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HL: Fachverband Halbleiterphysik

HL 36: Materials and Devices for Quantum Technology 2

HL 36.7: Vortrag

Donnerstag, 8. September 2022, 16:45–17:00, H36

Coherent interactions between confined fluids of light and GHz-phonons — •Alexander Kuznetsov, Klaus Biermann, and Paulo Santos — Paul-Drude-Institut für Festkörperelektronik in Forschungsverbund Berlin, e. V., Berlin, Germany

Microcavity exciton-polaritons are at the heart of an emerging field of polaromechanics, which studies coupling between polariton and mechanical degrees of freedom and promises unit quantum cooperativity. One challenge is to reach the regime of coherent interactions, when the polariton decoherence rate is smaller than mechanical frequency.

We reached this milestone by coupling polariton fluids of light (macroscopic quantum state) to GHz phonons. High-resolution optical spectroscopy revealed ns-long coherence time reaching τ = 2 ns. Monochromatic Ω_M = 7 GHz phonons were injected into a trap using acoustic transducers. Since 1/τ < Ω_M, the interaction resulted in the appearance of well-resolved phonon sidebands in the emission – an optical frequency comb. We demonstrated tuning of the sidebands by the phonon amplitude, which was controlled by the radio-frequency power applied to the transducer.

The demonstrated coherent polaromechanical device is a building block for a bi-directional interface between microwave and optical domains, atomic clocks, and is useful to study rich physics of sideband cooling and amplification.