Chiral Quantum Optics using Topological Photonics

Abstract

Topological photonics has opened new avenues to designing photonic devices along with opening a plethora of applications. Recently, even though there have been many interesting studies in topological photonics in the classical domain, the quantum regime has remained largely unexplored. In this thesis, I will demonstrate a recently developed topological photonic crystal structure for interfacing a single quantum dot spin with a photon to realize light-matter interaction with topolog-ical photonic states. Developed on a thin slab of Gallium Arsenide(GaAs) mem- brane with electron beam lithography, such a device supports two robust counter- propagating edge states at the boundary of two distinct topological photonic crystals at near-IR wavelength. I will show the chiral coupling of circularly polarized lights emitted from a single Indium Arsenide(InAs) quantum dot under a strong magnetic field into these topological edge modes. Owing to the topological nature of these guided modes, I will demonstrate this photon routing to be robust against sharp corners along the waveguide. Additionally, taking it further into the cavity-QED regime, we will build a topological photonic crystal resonator. This new type of resonator will be based on valley-Hall topological physics and sustain two counter- propagating resonator modes. Thanks to the robustness of the topological edge modes to sharp bends, the newly formed resonators can take various shapes, the simplest one being a triangular optical resonator. We will study the chiral coupling of such resonator modes with a single quantum dot emission. Moreover, we will show an intensity enhancement of a single dot emission when it resonantly couples with a cavity mode. This new topological photonic crystal platform paves paths for fault-tolerant complex photonic circuits, secure quantum computation, and explor- ing unconventional quantum states of light and chiral spin networks.