We are interested in fundamental aspects of quantum mechanics, e.g., quantum measurement problems, open quantum system approaches to quantum decoherence, and quantum thermodynamics. For quantum mechanics and quantum statistics, we believe that there are many problems which are not yet understood completely. We are not satisfied with investigating these problems only on the philosophical basis, but intend to have a "down-to-earth" understanding of them in association with the most recent experiments about circuit QED of superconducting systems, optomechanics with nano-mechanical resonators, the photon transport in low-dimensional confined structures, and the ultra-cold atoms in Bose-Einstein condensate.

Our current research interests belong in a broad sense to the field of physical implementation of quantum computing and quantum simulation idea, especially on experimental realization of quantum information processing with linear optics. Apart from the design of interactions and quantum gates this research also includes the analysis of decoherence source as well as state preparation and measurement techniques as prerequisites for quantum computations. Due to the interdisciplinary character of this research field we have become interested in various physical systems, both from the field of linear optics, the field of atomic, molecular and optical physics, as well as the field of solid state physics.

Various defect centers in solid-state materials (e.g., nitrogen- and silicon-vacancy centers in diamond, phosphorus donors in silicon, and rare earth ions in laser crystals) are promising candidate systems for quantum information processing. They also have broad applications in different fields, including quantum metrology and biological sensing. The understanding of the underlying physics of these defect centers are of great importance to the applications. In close collaboration with world's pioneering experimental groups, we are studying the rich quantum phenomena occurring in solid-state defect centers, particularly the spin dynamics and novel quantum optical processes.

Thermal atoms have broad applications such as ultra-sensitive magnetometer with alkali-metal vapor cells and inertial measurement unit based on spin-exchange pumping. We study the elementary physical processes behind these applications, including atom-photon interaction, atom-atom collision, and atomic spin decoherence, etc, both theoretically and experimentally. We will try to establish quantitative connections between the microscopic process and the ultimate performance in various applications, and to explore quantum resource which may lead to revolutionary techniques in the future applications.

Our main research interests include: (1) quantum optomechanics, e.g., the non-reciprocal photon/phonon transmission in optomechanical systems and mechanical sensing in (hybrid) optomechanical systems; (2) quantum optics in chiral molecules for such as separation and discrimination of enantiomers.

We both theoretically and experimentally explore scalable quantum computation using solid-state qubits, including the quantum computing with superconducting circuits, electron spins in quantum dots, and defects in solid-state materials. We also investigate hybrid quantum systems and explore their distinct advantages in quantum information processing.