272 research outputs found
Optical position meters analyzed in the non-inertial reference frames
In the framework of General Relativity we develop a method for analysis of
the operation of the optical position meters in their photodetectors proper
reference frames. These frames are non-inertial in general due to the action of
external fluctuative forces on meters test masses, including detectors. For
comparison we also perform the calculations in the laboratory (globally
inertial) reference frame and demonstrate that for certain optical schemes
laboratory-based analysis results in unmeasurable quantities, in contrast to
the detector-based analysis. We also calculate the response of the simplest
optical meters to weak plane gravitational waves and fluctuative motions of
their test masses. It is demonstrated that for the round-trip meter analysis in
both the transverse-traceless (TT) and local Lorentz (LL) gauges produces equal
results, while for the forward-trip meter corresponding results differ in
accordance with different physical assumptions (e.g. procedure of clocks
synchronization) implicitly underlying the construction of the TT and LL
gauges.Comment: 10 pages, 2 figures; co-author added, added section VC with
discussion of procedures of clocks synchronization, corrected sign in old
Eq.17 (currently it is Eq.18
Anomalous dynamic back-action in interferometers
We analyze the dynamic optomechanical back-action in signal-recycled
Michelson and Michelson-Sagnac interferometers that are operated off dark port.
We show that in this case --- and in contrast to the well-studied canonical
form of dynamic back-action on dark port --- optical damping in a
Michelson-Sagnac interferometer acquires a non-zero value on cavity resonance,
and additional stability/instability regions on either side of the resonance,
revealing new regimes of cooling/heating of micromechanical oscillators. In a
free-mass Michelson interferometer for a certain region of parameters we
predict a stable single-carrier optical spring (positive spring and positive
damping), which can be utilized for the reduction of quantum noise in
future-generation gravitational-wave detectors.Comment: 9 pages, 5 figures. Paper reorganize
Displacement-noise-free gravitational-wave detection with a single Fabry-Perot cavity: a toy model
We propose a detuned Fabry-Perot cavity, pumped through both the mirrors, as
\textit{a toy model} of the gravitational-wave (GW) detector partially free
from displacement noise of the test masses. It is demonstrated that the noise
of cavity mirrors can be eliminated, but the one of lasers and detectors
cannot. The isolation of the GW signal from displacement noise of the mirrors
is achieved in a proper linear combination of the cavity output signals. The
construction of such a linear combination is possible due to the difference
between the reflected and transmitted output signals of detuned cavity. We
demonstrate that in low-frequency region the obtained displacement-noise-free
response signal is much stronger than the -limited
sensitivity of displacement-noise-free interferometers recently proposed by S.
Kawamura and Y. Chen. However, the loss of the resonant gain in the noise
cancelation procedure results is the sensitivity limitation of our toy model by
displacement noise of lasers and detectors.Comment: 16 pages, 5 figures; extended discussion of basic mechanism of noise
cancelation moved to new Sec. II (with new figure), added discussion of laser
noise cancelation in Sec. VI D (with new figure
Observation of generalized optomechanical coupling and cooling on cavity resonance
Optomechanical coupling between a light field and the motion of a cavity
mirror via radiation pressure plays an important role for the exploration of
macroscopic quantum physics and for the detection of gravitational waves (GWs).
It has been used to cool mechanical oscillators into their quantum ground
states and has been considered to boost the sensitivity of GW detectors, e.g.
via the optical spring effect. Here, we present the experimental
characterization of generalized, that is, dispersive and dissipative
optomechanical coupling, with a macroscopic (1.5mm)^2-sized silicon nitride
(SiN) membrane in a cavity-enhanced Michelson-type interferometer. We report
for the first time strong optomechanical cooling based on dissipative coupling,
even on cavity resonance, in excellent agreement with theory. Our result will
allow for new experimental regimes in macroscopic quantum physics and GW
detection
Charged Particles and the Electro-Magnetic Field in Non-Inertial Frames of Minkowski Spacetime: II. Applications: Rotating Frames, Sagnac Effect, Faraday Rotation, Wrap-up Effect
We apply the theory of non-inertial frames in Minkowski space-time, developed
in the previous paper, to various relevant physical systems. We give the 3+1
description without coordinate-singularities of the rotating disk and the
Sagnac effect, with added comments on pulsar magnetosphere and on a
relativistic extension of the Earth-fixed coordinate system. Then we study
properties of Maxwell equations in non-inertial frames like the wrap-up effect
and the Faraday rotation in astrophysics.Comment: This paper and the second one are an adaptation of arXiv 0812.3057
for publication on Int.J.Geom. Methods in Modern Phys. 36
Interaction of plane gravitational waves with a Fabry-Perot cavity in the local Lorentz frame
We analyze the interaction of plane '+'-polarized gravitational waves with a
Fabry-Perot cavity in the local Lorentz frame of the cavity input mirror
outside of the range of long-wave approximation with the force of radiation
pressure taken into account. The obtained detector response signal is
represented as a sum of two parts: (i) the phase shift due to displacement of
the movable mirror under the influence of gravitational wave and the force of
light pressure, and (ii) the phase shift due to direct interaction of
gravitational wave with light wave inside the cavity. We obtain formula for the
movable mirror law of motion paying close attention to the phenomena of optical
rigidity, radiative friction and direct coupling of gravitational wave to light
wave. Some issues concerning the detection of high-frequency gravitational
waves and the role of optical rigidity in it are discussed. We also examine in
detail special cases of optical resonance and small detuning from it and
compare our results with the known ones.Comment: 17 pages, 9 figures; corrected references [7,8,34], added 2 new
references (currently [35,36]), added comments on (i) relativistic
corrections, (ii) detector angular pattern, (iii) quantized electromagnetic
field, increased font in figure
Low-frequency hemoviscoelastography in monitoring coagulation disorders after abdominal surgery for cancer
Trade-off between quantum and thermal fluctuations in mirror coatings yields improved sensitivity of gravitational-wave interferometers
We propose a simple way to improve the laser gravitational-wave detectors
sensitivity by means of reduction of the number of reflective coating layers of
the core optics mirrors. This effects in the proportional decrease of the
coating thermal noise, the most notorious among the interferometers technical
noise sources. The price for this is the increased quantum noise, as well as
high requirements for the pump laser power and power at the beamsplitter.
However, as far as these processes depend differently on the coating thickness,
we demonstrate that a certain trade-off is possible, yielding a 20-30% gain
(for diverse gravitational wave signal types and interferometer
configurations), providing that feasible values of laser power and power on the
beamsplitter are assumed.Comment: 11 pages, 4 figures, 4 table
The state of hemostasis in pregnant women with hydramnion
Purpose. To determine the state of various stages of hemostasis in pregnant women with
hydramnion as a risk factor for premature detachment of the placenta.
Results. There was investigated the state of hemostasis in pregnant women with hydramnion
by low piezoelectric thromboelastography (LPTEG) and standard coagulogram. According to
the LPTEG results this group of women was found to have increased plasma coagulation
potential manifested in elevated constant thrombin activity (TAC) by 76.8%, the intensity of
coagulation drive (ICD) by 74.9%, maximum clot density (MA) by 16.8%, shortening of
coagulation time (T3) by 7.8% and inhibition of fibrinolysis manifested by decrease in
retraction intensity and clot lysis (RICL) by 67.7% (p<0.05).
Conclusions. The state of hemostasis in pregnant women with hydramnion is characterized
by increased plasma coagulation and inhibition of fibrinolysis potential that are factors of
preparing the woman’s body for the upcoming birth to control and minimize blood loss
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