6,920 research outputs found
Optimal Alignment Sensing of a Readout Mode Cleaner Cavity
Critically coupled resonant optical cavities are often used as mode cleaners
in optical systems to improve the signal to noise ratio (SNR) of a signal that
is encoded as an amplitude modulation of a laser beam. Achieving the best SNR
requires maintaining the alignment of the mode cleaner relative to the laser
beam on which the signal is encoded. An automatic alignment system which is
primarily sensitive to the carrier field component of the beam will not, in
general, provide optimal SNR. We present an approach that modifies traditional
dither alignment sensing by applying a large amplitude modulation on the signal
field, thereby producing error signals that are sensitive to the signal
sideband field alignment. When used in conjunction with alignment actuators,
this approach can improve the detected SNR; we demonstrate a factor of 3
improvement in the SNR of a kilometer-scale detector of the Laser
Interferometer Gravitational-wave Observatory. This approach can be generalized
to other types of alignment sensors
Quantum Chaos in the Yang-Mills-Higgs System at Finite Temperature
The quantum chaos in the finite-temperature Yang-Mills-Higgs system is
studied. The energy spectrum of a spatially homogeneous SU(2) Yang-Mills-Higgs
is calculated within thermofield dynamics. Level statistics of the spectra is
studied by plotting nearest-level spacing distribution histograms. It is found
that finite temperature effects lead to a strengthening of chaotic effects,
i.e. spectrum which has Poissonian distribution at zero temperature has
Gaussian distribution at finite-temperature.Comment: 6 pages, 5 figures, Revte
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