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

2019-01-03T18:44:42Z (GMT) by Saman Jahani
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.

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
momentum of evanescent waves, an important electromagnetic property overlooked in photonic devices. For practical applications, we experimentally demonstrate
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.

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
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.

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.