Coherence, Dephasing, and Quantum Interference in Colloidal Perovskite Nanocrystals

Abstract

As the development of photonic quantum technologies continues to be pushed forward, the need for a source of quantum light, the so-called quantum emitter, has been ever-growing. The requirements for a quantum emitter are onerous: indistinguishable photon or entangled photon pairs need to be generated on-demand, which necessitates the presence of transform-limited emission. The hunt for ideal quantum emitters is ongoing: while there are many strong candidates, none meet all of the necessary requirements to enable the full capabilities of potential quantum technologies. Recently, colloidal cesium lead bromide perovskite nanocrystals have garnered interest for their potential use as quantum emitters. As a novel emitter, there is a prominent need for further characterization of perovskite nanocrystals, not only to learn more about the fundamental photophysics in these materials but also to establish their inherent properties as coherent sources of light.

In this thesis, I discuss what it means to be a quantum emitter, what it means for light to behave quantum mechanically, what kinds of quantum emitter properties are important, and how to measure those properties. I discuss the intrinsic capabilities of cesium lead halide perovskites, and what primes them to be the first colloidal quantum emitter. This thesis chronicles measuring Hong-Ou-Mandel (HOM) two-photon interference, the ubiquitous measure of quantum interference, showing HOM visibilities in colloidal materials for the first time. I also detail what types of experiments and further work can be done to build on what we know now, and hopefully provide insight into interesting future scientific inquiry.