Strain Tuning Self-Assembled Quantum Dots for Energy-Tunable Entangled-Photon Sources Using a Photolithographically Fabricated Microelectromechanical System

Self-assembled quantum dots (QDs) offer versatile sources of quantum light for photonic quantum technologies thanks to their atomic-like discrete energy levels for deterministic generation of single photons. Though, the unavoidable inhomogeneous broadening and the ubiquitous presence of the fine structure splitting (FSS) of the exciton states hamper their use as high-fidelity entangled-photon sources (EPSs) with well-defined energies, core elements in scalable networking quantum applications. To overcome these challenges, in this work, we propose and demonstrate a photolithographically fabricated microelectromechanical system (MEMS) to dynamically control the optical properties of QDs. The device features two orthogonal and independent uniaxial stresses that can tune the exciton energy and the FSS simultaneously, enabling demonstration of energy-tunable EPSs based on self-assembled QDs. The device can be processed by only employing standard photolithography techniques, which alleviates the use of sophisticated device design and fabrications, thus providing a viable route toward the realization of entanglement swapping with all-solid-state quantum emitters.