Ultrafast Spectroscopy & Quantum Optics

Research Overview

My group studies the interaction of light with matter by using cutting-edge optical tools. We are interested in many-body quantum systems consisting of interacting quantum entities. Examples include single atom arrays trapped by optical tweezers and color centers in diamonds. We develop and utilize techniques and ideas in ultrafast spectroscopy and quantum optics, such as multidimensional coherent spectroscopy and quantum entanglement, to probe and manipulate quantum dynamics of such systems. The group explores fundamental physics associated with these problems and facilitates potential applications in quantum information science and other fields.

Optical Multidimensional Coherent Spectroscopy

The concept of Multidimensional Coherent Spectroscopy originated in nuclear magnetic resonance (NMR) and revolutionized NMR studies of the structure and dynamics of bio-molecules. By using state-of-the-art femtosecond lasers, the same concept can be implemented in the optical region. Optical Multidimensional Coherent Spectroscopy has been proved to be a powerful tool for studying couplings and dynamics in complex systems. We use this technique to study many-body interactions and dynamics in atoms/molecules, semiconductor nanostructures and other solid state systems.

Ultrafast Spectroscopy and Manipulation of Quantum States in Atom Arrays

Neutral atoms trapped in an array of optical tweezers have recently attracted great interest due to potential applications in QIS. A key aspect of quantum computer/simulator is many-body effects due to interacting individuals in the system. An experimentally confirmed understanding of many-body interactions and correlations in an atomic ensemble, particularly an atom array, is essential for the implementation of atom-based quantum simulators. In this thrust, I plan to prepare an array of Rb cold atoms in a set of optical tweezers. I will use ultrafast spectroscopy to study manybody effects including interactions, correlations, and collective effects in atom arrays for applications in fundamental many-body physics and quantum technologies. I will also explore the possibility of ultrafast manipulation of quantum states in atom arrays by using femtosecond pulses.

Towards Coupled Quantum Emitter Arrays of Color Centers in Solids

In quantum information technologies, solid-state-based, on-demand single-photon-emitters (SPEs) are the fundamental building blocks for high-density, on-chip quantum circuits. One of the promising solid-state SPE systems is the color centers in diamonds. The spin states of a single color center can be initialized, manipulated, and read out at room temperature. However, it remains challenging to couple color centers. In this project, we plan to study the requirements to couple color centers in diamonds. We will fabricate SiV color center arrays by implanting a diamond substrate at precise locations by using a focused ion beam (FIB). The coupling between color centers will be probed with ultrafast coherent spectroscopy in samples with different fabrication parameters to understand the requirements.