Overview: Quantum Information Science and Many-Body Physics with Single Quantum Entities
In Quantum Information Science (QIS), to fully harness the power of quantum mechanics, the platform has to be a many-body system with interacting or coupled single quantum entities (or qubits). Experimentally understanding new principles and laws in few- and many-body systems is essential for both solving interesting puzzles in fundamental many-body physics and ultimately providing practical solutions for important technological applications in many fields including QIS.
The research in my group focuses on experimental studies of many-body quantum systems by using advanced optical techniques in ultrafast spectroscopy and quantum optics. Recent advances in the preparation of exotic single quantum entities (single atoms and atom-like solid-state materials) and in coherent spectroscopy provide unprecedented opportunities in the field. We are interested in many-body quantum systems consisting of such interacting quantum entities. Examples include atomic systems such as single atom arrays trapped by optical tweezers. In solid-state systems, we are interested in color centers in solids (e.g. SiV centers in diamonds and SiC), quantum dots, and 2D materials. In our studies, we deterministically prepare a few- or many-body quantum system of single quantum entities using a bottom-up approach and use the system for studying many-body properties and realizing applications in QIS. 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.
Some of our research projects are the follows.
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, color centers in solids, 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 project, we prepare an array of Rb cold atoms in a set of optical tweezers. Optical multi-dimensional coherent spectroscopy will be used to study manybody effects including interactions, correlations, and collective effects in atom arrays for applications in fundamental many-body physics and quantum technologies. We 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
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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 study the requirements to couple color centers in diamonds. We 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.
