Professor Deng's group's research centers on the coherence of many-body systems and the coherent interfaces between matter and light. It develops along two lines: Can quantum coherence exist in many-body systems, either spontaneously acquired or externally induced and preserved? How does that happen, how do we measure, manipulate, and utilize the macroscopic coherence in novel device application and in quantum information science?
At present, the first focus of my group is macroscopic coherence formed spontaneously in a thermodynamic phase transition, such as in BEC. One especially interesting system is the half-matter half-light quasi-particles in solids called exciton-polaritons, resulting from coherent strong coupling between a microcavity photon and an electron-hole pair in semiconductors. Polaritons have extremely light effective mass; hence can go through quantum phase transitions at liquid Helium to room temperatures. They also can be conveniently and directly studied by spectroscopic and quantum optics techniques. We characterize their thermodynamic and quantum statistical properties, search for evidence of quantum phases, and explored their applications as novel optoelectronics and spintronics devices, and as quantum simulators.
The second focus is using laser manipulation to coherently generate, preserve and control quantum states in semiconductors. Much progress has been made with atomic and trapped ion systems, yet semiconductors have unique advantages in speed, scalability and versatility. We are interested in finding, in a sense, ‘atomic-like’ solid state systems which have clean, stable, and optically accessible energy levels. One promising candidate is the impurity-bound electron spin ensemble in high purity semiconductors. The goal is to characterize their potential as qubits and/or quantum memories, and develop methods to control them for quantum information storage, processing and transfer.
Mapping Photonic Entanglement into and out of a Quantum Memory, (K. S. Choi, H. Deng, J. Laurat and H. J. Kimble), Nature 452, 67-71 (2008).
Functional Quantum Nodes for Entanglement Distribution over Scalable Quantum Networks, (C. W. Chou, J. Laurat, H. Deng, K. S. Choi, H. De Riedmatten, D. Felinto and H. J. Kimble), Science 316, 1316 (2007).
Spatial Coherence of a Polariton Condensate, (H. Deng, S. S. Glenn, H. Rudolf, H. P. Klaus and Y. Yoshihisa), Physical Review Letters 99, 126403 (2007).
Quantum Degenerate Exciton-Polaritons in Thermal Equilibrium, (H. Deng, D. Press, S. Gotzinger, G. S. Solomon, R. Hey, K. H. Ploog and Y. Yamamoto), Physical Review Letters 97, 146402 (2006).
Polariton Lasing vs. Photon Lasing in a Semiconductor Microcavity, (H. Deng, G. Weihs, D. Snoke, J. Bloch and Y. Yamamoto), Proceedings of the National Academy of Sciences of the United States of America 100, 15318-15323 (2003).
Condensation of Semiconductor Microcavity Exciton Polaritons, (H. Deng, G. Weihs, C. Santori, J. Bloch and Y. Yamamoto), Science 298, 199-202 (2002).