Phonon engineering around a single photon emitter

• Applicant: Dr. Martin Esmann
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2018 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 401390650

In the development of solid-state quantum technologies, phonons play a key role as a source of decoherence. The aim of this project is to explore the optical properties of single semiconductor quantum dots deterministically coupled to nanomechanical cavities confining ultra-high frequency phonon modes in the GHz-THz range. Single quantum dots coupled to optical microcavities are at the base of bright sources for indistinguishable single-photons. In this context, the coupling between quantum dots and confined mechanical modes has, however, remained greatly unexplored. A striking result has recently been reported: the same GaAs/AlAs micropillars used for the fabrication of quantum dot-based single photon sources are simultaneously an optimal acoustic-phonon resonator in the 20 GHz range. Using the same tools previously developed to deterministically couple a quantum dot to an optical mode, it is thus possible to engineer the coupling of a single quantum dot to a mechanical mode. In this way, phonons in the cavity can be used to modulate the optical emission properties of the quantum dot at GHz-THz frequencies, and photons can be used to generate single phonons in the same system. We aim at demonstrating experimentally first phenomena evidencing these interactions between a single QD and a confined ultra-high frequency phononic mode, bridging the gap between the two fields of quantum optics and nanophononics. We envisage two major experimental goals: (i) To demonstrate the accelerated emission of phonons by a single QD (the phononic Purcell effect) and (ii) To modulate the optical emission of a single QD at GHz-THz frequencies by monochromatic acoustic phonons. These results could have a major impact on the conception of future solid-state quantum technology devices and could be at the base of novel quantum information protocols using acoustic phonons as a main carrier of information.

• DFG Programme: Research Fellowships
• International Connection: France
• Host: Dr. Norberto Daniel Lanzillotti-Kimura