On-Chip Quantum Photonics: Low Mode Volumes, Nonlinearities and Nano-Scale Superconducting Detectors

<div>Miniaturization of optical components with low power consumption fabricated using a CMOS foundry process can pave the way for dense photonic integrated circuits and on-chip quantum information processing. Optical waveguides, modulators/switches, and single-photon detectors are the key components in any photonic circuits, and miniaturizing them is challenging. This requires strong control of evanescent waves to reduce the cross-talk and bending loss as well as low mode volumes to increase light-matter interaction.</div><div><br></div><div><div>In this thesis, we propose a paradigm shift in light connement strategy using transparent all-dielectric metamaterials. Our approach relies on controlling the optical</div><div>momentum of evanescent waves, an important electromagnetic property overlooked in photonic devices. For practical applications, we experimentally demonstrate</div><div>photonic skin-depth engineering on a silicon chip to conne light and to reduce the cross-talk and bending loss in a dense photonic integrated circuit.</div></div><div><br></div><div><div>We demonstrate that due to the strong light connement in the proposed waveguides, it is possible to miniaturize and integrate superconducting nanowire singlephoton detectors (SNSPDs) into a silicon chip. The timing jitter and dark-count</div><div>rate in these miniaturized SNSPDs can be considerably reduced. Here, we propose a theoretical model to understand the fundamental limits of these nanoscale SNSPDs and the trade-off between timing jitter, dark-count, and quantum effciency in these detectors. We propose experimental tests to verify the validity of our model.</div></div><div><br></div><div><div>Switching/modulating cavity Purcell factor on-chip is challenging, so we have proposed a nonlinear approach to switch Purcell factors in epsilon near zero (ENZ) materials. We demonstrate fourfold change in the Purcell factor with a switching time of 50 fs. The work in this thesis can lead to a unique platform for on-chip quantum nanophotonics.</div></div>