Waveguide-QED and entangled photon generation from a quantum dot in a waveguide - Tarun Patel

A two-level quantum system coupled to a one-dimensional electromagnetic mode has been a long-sought-after goal in quantum electrodynamics for the realization of the so-called “One-dimensional atom.” Such a system would enable the realization of key components for quantum networks, such as single or entangled photon sources, photon-photon gates, and spin-photon entanglement. An InAsP quantum dot placed on the axis of a InP nanowire waveguide is an ideal system to achieve this goal. In this talk, I will present recent work done in collaboration with NRC-Canada to systematically investigate and improve the performance of such a nanowire quantum dot (NWQD) system. The first half of the presentation will focus on implementing near-unity in- and out-coupling of light from the nanowire waveguide into an optical fiber. This allows us to extend the waveguide mode from a 4K cryostat system to the outside world. Using this system, we perform Rayleigh scattering from the quantum dot without requiring any additional filtering technique for the first time, demonstrating a robust realization of a “One-dimensional atom.” In the second half, I will present the use of the NWQD system as an entangled photon pair source and recent improvements obtained in source efficiency by implementing a bottom gold mirror using a ‘pick-and-place’ technique in a FIB-SEM system.