36 research outputs found
Classical Nature of the Inflaton Field with Self-Interaction
Taking into account the effect of self-interaction, the dynamics of the
quantum fluctuations of the inflaton field with potential is
studied in detail. We find that the self interaction efficiently drives the
initial pure state into a mixed one, which can be understood as a statistical
ensemble. Further, the expectation value of the squared field operator is found
to be converted into the variance of this statistical ensemble without giving
any significant change in its amplitude. These results verify the ansatz of the
quantum-to-classical transition that has been assumed in the standard
evaluation of the amplitude of the primordial fluctuations of the universe.Comment: 23 pages, submitted to Phys. Rev. D1
Self-gravitating Stellar Systems and Non-extensive Thermostatistics
After introducing the fundamental properties of self-gravitating systems, we
present an application of Tsallis' generalized entropy to the analysis of their
thermodynamic nature. By extremizing the Tsallis entropy, we obtain an equation
of state known as the stellar polytrope. For a self-gravitating stellar system
confined within a perfectly reflecting wall, we discuss the thermodynamic
instability caused by its negative specific heat. The role of the extremum as a
quasi-equilibrium is also demonstrated from the results of N-body simulations.Comment: 15 pages, 8 figures, final version to apper in CM
Quantum Noise in Differential-type Gravitational-wave Interferometer and Signal Recycling
There exists the standard quantum limit (SQL), derived from Heisenberg's
uncertainty relation, in the sensitivity of laser interferometer
gravitational-wave detectors. However, in the context of a full
quantum-mechanical approach, SQL can be overcome using the correlation of shot
noise and radiation-pressure noise. So far, signal recycling, which is one of
the methods to overcome SQL, is considered only in a recombined-type
interferometer such as Advanced-LIGO, LCGT, and GEO600. In this paper, we
investigated quantum noise and the possibility of signal recycling in a
differential-type interferometer. As a result, we found that signal recycling
is possible and creates at most three dips in the sensitivity curve of the
detector. Then, taking advantage of the third additional dip and comparing the
sensitivity of a differential-type interferometer with that of a
next-generation Japanese GW interferometer, LCGT, we found that SNR of inspiral
binary is improved by a factor of 1.43 for neutron star binary, 2.28 for 50
M_sun black hole binary, and 2.94 for 100 M_sun black hole binary. We also
found that power recycling to increase laser power is possible in our
signal-recycling configuration of a detector.Comment: 17 pages, submitted to Phys.Rev.
Resonant speed meter for gravitational wave detection
Gravitational-wave detectors have been well developed and operated with high
sensitivity. However, they still suffer from mirror displacement noise. In this
paper, we propose a resonant speed meter, as a displacement noise-canceled
configuration based on a ring-shaped synchronous recycling interferometer. The
remarkable feature of this interferometer is that, at certain frequencies,
gravitational-wave signals are amplified, while displacement noises are not.Comment: 4 pages, 4 figure