185 research outputs found
Quasi-Eigenstate Evolution in Open Chaotic Billiards
We experimentally studied evolution of quasi-eigenmodes as classical dynamics
undergoing a transition from being regular to chaotic in open quantum
billiards. In a deformation-variable microcavity we traced all high-Q cavity
modes in a wide range of frequency as the cavity deformation increased. By
employing an internal parameter we were able to obtain a mode-dynamics diagram
at a given deformation, showing avoided crossings between different mode
groups, and could directly observe the coupling strengths induced by ray chaos
among encountering modes. We also show that the observed mode-dynamics diagrams
reflect the underlying classical ray dynamics in the phase space.Comment: 4 pages, 4 figure
A definitive number of atoms on demand: controlling the number of atoms in a-few-atom magneto-optical trap
A few 85Rb atoms were trapped in a micron-size magneto-optical trap with a
high quadrupole magnetic-field gradient and the number of atoms was precisely
controlled by suppressing stochastic loading and loss events via real-time
feedback on the magnetic field gradient. The measured occupation probability of
single atom was as high as 99%. Atoms up to five were also trapped with high
occupation probabilities. The present technique could be used to make a
deterministic atom source.Comment: 3 pages, 4 figure
Development of deformation-tunable quadrupolar microcavity
We have developed a technique for realizing a two-dimensional quadrupolar
microcavity with its deformation variable from 0% to 20% continuously. We
employed a microjet ejected from a noncircular orifice in order to generate a
stationary column with modulated quadrupolar deformation in its cross section.
Wavelength red shifts of low-order cavity modes due to shape deformation were
measured and were found to be in good agreement with the wave calculation for
the same deformation, indicating the observed deformation is quadrupolar in
nature.Comment: 7 pages, 6 figures, intended for Rev. Sci. Instu
A method of measuring the amplitude-modulated vacuum field near a conducting mirror
Electromagnetic fields of the vacuum mode near a conducting mirror are modified with respect to those in free space, with their amplitudes having a sinusoidal spatial dependence from the mirror. Therefore if we combine this spatially amplitude-modulated vacuum field mode and intense coherent light with a beam splitter, we may detect this fluctuation of the vacuum mode in a homodyne detection scheme. It will give a new method to produce squeezed states of light with a single mirror placed close to an unused port of a beam splitter. We show that the amplitude fluctuation of the combined light can be reduced by a factor of 2 below that of the coherent light. We also discuss the limitations due to the finite line width of the laser and the effective absorption length of the photodiodes
Chaos-assisted nonresonant optical pumping of quadrupole-deformed microlasers
Efficient nonresonant optical pumping of a high-Q scar mode in a
two-dimensional quadrupole-deformed microlaser has been demonstrated based on
ray and wave chaos. Three-fold enhancement in the lasing power was achieved at
a properly chosen pumping angle. The experimental result is consistent with ray
tracing and wave overlap integral calculations.Comment: 3 pages, 5 figure
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