Using Machine-Learning Assisted Design for Reduction of the Quantum Decoherence in Room-Temperature Integrated Quantum Photonics

The development of on-chip, CMOS-compatible quantum photonics is critical for future scalable quantum communications, quantum computing, and quantum sensing. Integrated photonic waveguides, photonic resonators, and single-photon emitters are essential building blocks for such a purpose. In this talk, I will present how machine learning (ML) can enhance the quantum properties of these building blocks, specifically the indistinguishability (<i>I</i>) of the generated single photons, with a further decrease in quantum decoherence. The model has been numerically evaluated through finite-difference time-domain (FDTD) simulations, showing consistent results. Also, we explored a hybrid slot-Bragg nanophotonic cavity to generate indistinguishable photons at RT from various quantum emitters through a combination of numerical methods. To relax the fabrication requirements (slot width) for near-unity <i>I</i>, we used an ML algorithm that provides the optimal geometry of the cavity. [1] Finally, we have developed a theory for estimating <i>I</i> in a two-emitter system with strong dephasing coupled to a single-mode cavity. We have derived an analytical expression of <i>I</i> as a function of the distance between the emitters, cavity decay rate, and pure dephasing rate. The results show how the requirements of the cavity for high <i>I</i> change with the strength of the dipolar interaction. We propose a new interpretation of the <i>I</i> value, which allows us to estimate its behavior with larger systems (i.e., systems with more than two emitters). We performed numerical simulations of five dipole-coupled emitters to find the optimal configuration for maximum <i>I</i>. For the optimization process, we developed a novel ML scheme based on a hybrid neural network (NN)-genetic algorithm (GA) to find the position of each emitter to maximize <i>I</i>. [2] The optimization procedure provides perfect <i>I </i>(i.e., <i>I</i> = 1) in arbitrary low Q cavities, offering relaxation of the cavity parameters and favoring emission from quantum emitters at room T.<br/><b>References:</b><br/>[1] J. Guimbao et al. ACS Photonics (2022), 9, 6, 1926-1935.<br/>[2] J. Guimbao et al. <i>Nanomaterials</i> 2022, <i>12</i>(16), 2800