Phonon engineering around a single photon emitter

在固体量子技术的发展中，声子作为退相干源起着关键作用。本项目的目的是探索单个半导体量子点与纳米机械腔的光学特性，这些腔限制在GHz-THz范围内的超高频声子模式。与光学微腔耦合的单量子点是难以区分的单光子明亮光源的基础。在这种情况下，量子点和受限力学模式之间的耦合仍然是一个很大的未知问题。最近报道了一个惊人的结果：用于制造基于量子点的单光子源的相同的GaAs/AlAs微柱同时是20 GHz范围内的最佳声子谐振器。使用先前开发的确定耦合量子点与光学模式的相同工具，因此可以设计单个量子点与机械模式的耦合。这样，腔中的声子可以用来调制量子点在GHz-THz频率下的光学发射特性，光子可以用来在同一系统中产生单个声子。我们的目标是通过实验证明单个量子点和受限的超高频声子模式之间的相互作用，弥合量子光学和纳米声子两个领域之间的差距。我们设想了两个主要的实验目标：(i)证明单个量子点的声子加速发射（声子珀塞尔效应）和（ii）通过单色声子调制单个量子点在GHz-THz频率上的光学发射。这些结果可能对未来固态量子技术设备的概念产生重大影响，并可能成为使用声子作为信息主要载体的新型量子信息协议的基础。

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.