969 research outputs found
Photon correlation in GaAs self-assembled quantum dots
We report on photon coincidence measurement in a single GaAs self-assembled
quantum dot (QD) using a pulsed excitation light source. At low excitation,
when a neutral exciton line was present in the photoluminescence (PL) spectrum,
we observed nearly perfect single photon emission from an isolated QD at 670 nm
wavelength. For higher excitation, multiple PL lines appeared on the spectra,
reflecting the formation of exciton complexes. Cross-correlation functions
between these lines showed either bunching or antibunching behavior, depending
on whether the relevant emission was from a biexciton cascade or a charged
exciton recombination.Comment: 5 pages, 3 figure
Cryogenic measurement of the optical absorption coefficient in sapphire crystals at 1.064(micro)m for the Large-scale Cryogenic Gravitational wave Telescope
We have applied laser calorimetry to the measurement of optical absorption in
mono-crystalline sapphire at cryogenic temperatures. Sapphire is a promising
candidate for the mirror substrates of the Large-scale Cryogenic Gravitational
wave Telescope. The optical absorption coefficients of different sapphire
samples at a wavelength of 1.064(micro)m at 5K were found to average 90ppm/cm.Comment: 8 pages, accepted to Phys. Lett.
Direct Measurement of Thermal Fluctuation of High-Q Pendulum
We achieved for the first time a direct measurement of the thermal
fluctuation of a pendulum in an off-resonant region using a laser
interferometric gravitational wave detector. These measurements have been well
identified for over one decade by an agreement with a theoretical prediction,
which was derived by a fluctuation-dissipation theorem. Thermal fluctuation is
dominated by the contribution of resistances in coil-magnet actuator circuits.
When we tuned these resistances, the noise spectrum also changed according to a
theoretical prediction. The measured thermal noise level corresponds to a high
quality factor on the order of 10^5 of the pendulum.Comment: 10 pages, 4 figure
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