Polariton-driven phonon laser

Abstract

Efficient generation of phonons is an important ingredient for a prospective electrically-driven phonon laser. Hybrid quantum systems combining cavity quantum electrodynamics and optomechanics constitute a novel platform with potential for operation at the extremely high frequency range (30–300 GHz). We report on laser-like phonon emission in a hybrid system that optomechanically couples polariton Bose-Einstein condensates (BECs) with phonons in a semiconductor microcavity. The studied system comprises GaAs/AlAs quantum wells coupled to cavity-confined optical and vibrational modes. The non-resonant continuous wave laser excitation of a polariton BEC in an individual trap of a trap array, induces coherent mechanical self-oscillation, leading to the formation of spectral sidebands displaced by harmonics of the fundamental 20 GHz mode vibration frequency. This phonon “lasing” enhances the phonon occupation five orders of magnitude above the thermal value when tunable neighbor traps are red-shifted with respect to the pumped trap BEC emission at even harmonics of the vibration mode. These experiments, supported by a theoretical model, constitute the first demonstration of coherent cavity optomechanical phenomena with exciton polaritons, paving the way for new hybrid designs for quantum technologies, phonon lasers, and phonon-photon bidirectional translators.

GHz guided optomechanics in planar semiconductor microcavities

“…As discussed in the previous section, further experimental studies are needed to clarify the modulation processes in this regime. Here, a promissing approach is the investigation of the interaction of gAPs with polaritons confined within 𝜇𝑚-sized intracavity traps in structured microcavities [37,[45][46][47]. We anticipate that the fabrication process of these structured MCs is fully compatible with the ones with acoustic WGs studied in this work.…”

“…Polariton confinement significantly reduces the polariton condensation threshold. In addition, the decoherence rate of confined polariton condensates can reach values 𝛾 𝑝𝑜𝑙 < 1 GHz much lower than the phonon frequency, thus enabling acoustic modulation in the sideband-resolved regime [37]. Prospects for future studies thus include the coherent GHz modulation of confined polaritons condensates [29] as well as phonon-mediated coupling and interconnection of intracavity polariton traps [45,46,48].…”

“…These particles are specially interesting for optomechanics due to the long spatial and, in the BEC state, temporal coherences as well as the strong resonant interactions with phonons mediated by their excitonic component. [8,29,[35][36][37][38][39]. The strong overlap of the acoustic and optoelectronic fields in the MC space induces a huge modulation of the strength (>80%) and energies (up to 3 meV) of the polariton resonances, which then become a sensitive local probe of the phonon fields.…”

Remote Phonon Control of Quantum Dots and Other Artificial Atoms

“…[134] Recently even phonon lasing was demonstrated in such a structure. [135] In the theoretical model of the laser, a three level system was applied and the laser transition between the exciton and the ground state was modulated as described in Section 2. This approach allows to study the laser process and its involved timescales systematically.…”

Theory of waveguide QED with moving emitters

“…A paradigmatic example could be optical lattices, either generated by optical waveguides [6][7][8], coupled to optical cavities [23] or mechanical modes [24], or tailored such that the roles of qubit motion and photonic modes are played by other degrees of freedom, such as spin states [25], different species of quantum emitters [26,27], or free (untrapped) atomic transitions [4,28,29]. An alternative possibility to engineer the above interactions is to use mechanical degrees of freedom, either in the form of acoustic waves modulating optical waveguides [30] or in the form of acoustic lattices for other particles and quasiparticles, such as electrons [31] or exciton-polaritons [32,33]. Implementations in microwave quantum devices could also be engineered using, e.g., flying Rydberg atoms [34].…”