Speaker: Dr. Disheng Chen, Nanyang Technological University, Singapore

Host: Prof. Gangqin Liu, Lab of Solid State Quantum Information & Computation

Time:  10:00, December 22, 2021

Abstract:

Resonance fluorescence (RF) from solid-state quantum emitters is of paramount importance for quantum information applications pivoted on two-photon interference, such as linear optical quantum computing and large-scale quantum networks. However, most solid-state emitters suffer from large inhomogeneous broadening, photoluminescence blinking and even a complete quenching of RF. Quite often, these phenomena are attributed to the uncontrolled local Fermi-level pinning or fluctuations due to the low but non-negligible background doping of the host materials, such as nitrogen and boron doping in diamond, or carbon and silicon doping in GaAs. In this talk, I will discuss an all-optical method to modify the local Fermi level around a Germanium-vacancy (GeV) color center in diamond, that in turn provides a two-orders of magnitude enhancement in RF emission. Meanwhile, the challenges posed by the spectral diffusion caused by environmental fluctuations and energy mismatch among different quantum emitters can be potentially reconciled with coherent scattering. We propose to use a 3-level V-system (such as InGaAs/GaAs quantum dots) to enhance the coherent scattering intensity and purity.

Brief CV of Dr. Disheng Chen:

Disheng Chen obtained a Ph.D. degree in condensed matter physics in 2017 by studying the resonance fluorescence from self-assembled semiconductor quantum dots in Prof. Edward Flagg group, USA. Afterwards, he joined IFW Dresden, Germany as a postdoc to study the spin properties of nanohole filling GaAs/AlGaAs semiconductor quantum dots. From 2018 to now, he is a research fellow in Weibo Gao’s quantum photonics group at NTU, Singapore, focusing on spin dynamics of quantum emitters in wide band-gap materials and developing spin–photon interface for quantum network applications.