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(From left to right, front row: David, Kai-Mei, Eleni,
Susan, Katsuya; second row: Young Chul, Stephan,
Chia-Yu, Bingyang, Shin’ichi, Yoshi, Third row: Kaoru, Neil, Thaddeus, Kristiaan,
Hiroki) Semiconductor systems provide robust and high-speed single-photon sources
and single-photon detectors at wide wavelength range from visible to near
infrared. A series of experiment have been performed in our group to generate
single photons using a single semiconductor quantum-dot (QD) in
micro-cavities and also single-photon detectors using periodically-poled
Lithium Niobate (PPLN) and silicon avalanche photodiodes. These components
are the key building-blocks for the applications of quantum key distribution
and quantum repeaters. One of the hottest topics in our group is the
donor-bound exciton system in GaAs substrate. A Zeeman sub-levels of a bound electron spin state
in the system provide metastable ground states, together with a lowest bound exciton state,
forms a so-called three-level lambda system. The first coherent population
transformation has been performed via coherent Raman process with a
solid-state semiconductor system. 1.
Single Photon
and Entangled-pair Source 4. Coherent
control in Semiconductors B. Quantum Many-Body
Systems and Quantum Simulation
(From left to right, front row: Hui, Neil, Yoshi, Na
Young; second row: George, Shoko, Shinichi; last Row: Tim, David,
Patrik, Cyrus, Fumiko) Quantum mechanics
is a successful framework to describe statics and dynamics of individual and
ensembles of constituting particles at the atomic and subatomic levels. It
provides microscopic understanding of phenomena in nature by establishing
Hamiltonian of the system and finding out the ground state properties. It becomes
unavoidable to encounter the system ground state including interactions
amongst participating entities; however it is a daunting and impossible task
to handle all degrees of freedom with enormous numbers of particles exactly.
Quantum statistics plays a crucial role to make a conjunction between
macroscopic thermodynamic properties and microscopic quantities by treating
effectively many-body interaction. Here we examine
various systems to observe quantum phase transition in the ground states
arising from fundamental correlations innate in systems via experimental
probes and theoretical tools. In particular, quantum simulation is a distinct
approach to perceive unresolved quantum phenomena since its underlying
philosophy lies on the fact that building
quantum system which emulate other quantum systems not only in solid
state systems but also in atomic physics, quantum optics, quantum chemistry
and so on. This area will provide new insights to assess interesting
questions existent in nature. 1.
Quantum
Statistics in Two-Dimensional Electron Gas Systems 2. Exciton Polariton
Bose-Einstein Condensation 3. Tomonaga-Luttinger
Liquid in Carbon Nanotubes 4. Quantum Simulation of Hubbard Models 5.
Quantum Simulation
of Lattice Gauge Models 6.
Quantum Simulation of Spin Models
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Last
Update: K.Sanaka on April24, 2006