Advanced design tools are critical for the progress of any technology platform, and this will be no less true for quantum technologies. We aim to develop advanced modelling tools for single-photon sources (SPS), the key enabling components of quantum communication networks (QCN). QCN are unhackable channels for communicating through light, whose ultimate security is guaranteed by the laws of quantum mechanics. Unamplified optical fibre links can transmit data up to ~100 km; there is a clear need to increase this range by introducing signal-booster stations. Launching these innovative systems on satellites solves this problem, as free-space light transmission suffers minimal absorption and scattering in Earth’s atmosphere, and overcomes issues with ground-based beaming due to Earth’s curvature. Semiconductor quantum dots (QDs) are one of the most promising solid-state SPS: they are bright, robust, fast, scalable, and generate on-demand single photons with >99% fidelity. At Quantopticon, we develop Quantillion: state-of-the-art quantum-enabled software for quantum-optical component modelling and optimisation. We recently demonstrated a giant optical phase shift (∼±π/2) of a circularly polarised pulse in a QD-micropillar cavity [G. Slavcheva, M. Koleva et al., PRB, 99 115433 (2019)]. We can model QDs made of any material – including GaN, operating at relatively high temperatures reachable by compact, lightweight thermoelectric cooling. Our in silico designs can establish the parameters needed for reliably and repeatably producing entangled photon states, a prerequisite for all QKD protocols. We seek to develop a quantum-mechanical framework to describe the non-classical light emitted by SPS, and to guide the manufacturing of controlled phase-shift quantum logic gates to perform effective entanglement on a large scale. This project will culminate in miniaturised, low-power chip-integrated QKD subsystems: essential for space deployment of high-quality, high-capacity QCN.
