Overview of Quantum Optics and Optical Materials
Research
Naoshi Uesugi
Physical Science Laboratory
In the fields of quantum optics and optical
materials we pursue our studies for the development
of core-technologies that will innovate optical
communications and optical signal processing
as well as for the scientific progress of
the field. Optical State Control Research
Group, Ultrafast Optical Physics Research
Group and Optical Device Physics Research
Group are engaged in the subjects listed
below.
Quantum State Control Research Group
(1) Quantum information processing (proposal
and verification of a new quantum cryptography,
studies on quantum protocols and quantum
computing).
(2) Soliton quantum optics (achievement of
soliton quantum nondemolition measurements
(QND), study of soliton squeezing).
(3) Atom optics (experimental and theoretical
studies on Bose-Einstein condensation of
alkali atoms, and nonlinear spectroscopy
of cold atoms).
(4) Theoretical study of excitons in low-dimensional
semiconductor structures (clarification of
optical and electrical properties of quantum
dots and dot arrays).
Ultrafast Optical Physics Research Group
(1) High-irradiance soft X-ray generation
from femtosecond laser produced plasma and
its application to materials science (demonstration
of high-irradiance soft X-ray pulse generation
and table-top soft X-ray laser, clarification
of soft X-ray generation mechanism, and demonstration
of time-resolved soft X-ray spectroscopy).
(2) Ultrafast coherent optical interaction
(ultrafast optical nonlinearities in low-dimensional
semiconductors, and coherent transient phenomenon
in rare-earth doped materials).
Optical Device Physics Research Group
(1) Optical properties of low-dimensional
semiconductors and their device applications
(experimental study of excitonic properties
of quantum disks, spin-polarized electron
transport in quantum wires, and polarization
control of semiconductor lasers by manipulating
electron spin).
(2) Fabrication process of low-dimensional
semiconductors (dry etching process for damage-
free surfaces of GaAs and GaN, and study
of molecular beam selective etching process).
(3) Evaluation of local optical properties
of low-dimensional semiconductors on the
nanometer scale (near-field optics by nanometer
optical probe).
(4) Studies on nitride-semiconductor quantum
well structures (optical properties of nitride
quantum well, and theoretical study of energy
band structure in nitride semiconductors).
Major results obtained this fiscal year 1999
are reported in the following pages. We elucidated
the dynamics of evaporative cooling, which
is employed to reach Bose-Einstein condensation
(BEC), by a quantum-kinetic analysis that
is applicable to both alkali-metal and hydrogen
atoms. Time-resolved measurement of soft
X-ray absorption was successfully demonstrated
by means of pump-probe spectroscopy, where
we employed a combination of femtosecond
laser pulses and synchronized soft X-ray
pulses emitted from the laser-induced plasma.
It was also experimentally demonstrated that
the optically spin-polarized electrons in
a GaAs quantum wire can propagate more than
10 mm while maintaining a relatively high
spin polarization.
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