2,685 research outputs found
Temperature of a Decoherent Oscillator with Strong Coupling
The temperature of an oscillator coupled to the vacuum state of a heat bath
via ohmic coupling is non-zero, as measured by the reduced density matrix of
the oscillator. This paper shows that the actual temperature, as measured by a
thermometer is still zero (or in the thermal state of the bath, the temperature
of the bath). The decoherence temperature is due to "false-decoherence", with
the heat bath state being dragged along with the oscillator.Comment: 6 page
Short-Time Decoherence and Deviation from Pure Quantum States
In systems considered for quantum computing, i.e., for control of quantum
dynamics with the goal of processing information coherently, decoherence and
deviation from pure quantum states, are the main obstacles to fault-tolerant
error correction. At low temperatures, usually assumed in quantum computing
designs, some of the accepted approaches to evaluation of relaxation mechanisms
break down. We develop a new general formalism for estimation of decoherence at
short times, appropriate for evaluation of quantum computing architectures.Comment: 9 pages in plain Te
Inappropriateness of the Rindler quantization
It is argued that the Rindler quantization is not a correct approach to study
the effects of acceleration on quantum fields. First, the "particle"-detector
approach based on the Minkowski quantization is not equivalent to the approach
based on the Rindler quantization. Second, the event horizon, which plays the
essential role in the Rindler quantization, cannot play any physical role for a
local noninertial observer.Comment: 3 pages, accepted for publication in Mod. Phys. Lett.
Design and test of aircraft engine isolators for reduced interior noise
Improved engine vibration isolation was proposed to be the most weight and cost efficient retrofit structure-borne noise control measure for single engine general aviation aircraft. A study was carried out the objectives: (1) to develop an engine isolator design specification for reduced interior noise transmission, (2) select/design candidate isolators to meet a 15 dB noise reduction design goal, and (3) carry out a proof of concept evaluation test. Analytical model of the engine, vibration isolators and engine mount structure were coupled to an empirical model of the fuselage for noise transmission evaluation. The model was used to develop engine isolator dynamic properties design specification for reduced noise transmission. Candidate isolators ere chosen from available product literature and retrofit to a test aircraft. A laboratory based test procedure was then developed to simulate engine induced noise transmission in the aircraft for a proof of concept evaluation test. Three candidate isolator configurations were evaluated for reduced structure-borne noise transmission relative to the original equipment isolators
Engine isolation for structural-borne interior noise reduction in a general aviation aircraft
Engine vibration isolation for structural-borne interior noise reduction is investigated. A laboratory based test procedure to simulate engine induced structure-borne noise transmission, the testing of a range of candidate isolators for relative performance data, and the development of an analytical model of the transmission phenomena for isolator design evaluation are addressed. The isolator relative performance test data show that the elastomeric isolators do not appear to operate as single degree of freedom systems with respect to noise isolation. Noise isolation beyond 150 Hz levels off and begins to decrease somewhat above 600 Hz. Coupled analytical and empirical models were used to study the structure-borne noise transmission phenomena. Correlation of predicted results with measured data show that (1) the modeling procedures are reasonably accurate for isolator design evaluation, (2) the frequency dependent properties of the isolators must be included in the model if reasonably accurate noise prediction beyond 150 Hz is desired. The experimental and analytical studies were carried out in the frequency range from 10 Hz to 1000 Hz
Quantum field and uniformly accelerated oscillator
We present an exact treatment of the influences on a quantum scalar field in
its Minkowski vacuum state induced by coupling of the field to a uniformly
accelerated harmonic oscillator. We show that there are no radiation from the
oscillator in the point of view of a uniformly accelerating observer. On the
other hand, there are radiations in the point of view of an inertial observer.
It is shown that Einstein-Podolsky-Rosen (EPR) like correlations of Rindler
particles in Minkowski vacuum states are modified by a phase factor in front of
the momentum-symmetric Rindler operators. The exact quantization of a
time-dependent oscillator coupled to a massless scalar field was given.Comment: 28 pages, LaTe
Decay Rate and Low-Energy Near-Horizon Dynamics of Acoustic Black Holes
We study the low-energy dynamics of an acoustic black hole near the sonic
horizon. For the experimental test of black hole evaporation in the laboratory,
the decay rate (greybody factor) of the acoustic black hole (sonic hole) can be
calculated by the usual low-energy perturbation method. As a consequence, we
obtain the decay rate of the sonic horizon from the absorption and the
reflection coefficients. Moreover, we show that the thermal emission from the
sonic horizon is only proportional to a control parameter which describes the
velocity of the fluid.Comment: 13pages, 3figures, RevTeX3, some minors corrected. version to appear
in PL
Radiation Reaction fields for an accelerated dipole for scalar and electromagnetic radiation
The radiation reaction fields are calculated for an accelerated changing
dipole in scalar and electromagnetic radiation fields. The acceleration
reaction is shown to alter the damping of a time varying dipole in the EM case,
but not the scalar case. In the EM case, the dipole radiation reaction field
can exert a force on an accelerated monopole charge associated with the
accelerated dipole. The radiation reaction of an accelerated charge does not
exert a torque on an accelerated magnetic dipole, but an accelerated dipole
does exert a force on the charge. The technique used is that originally
developed by Penrose for non-singular fields and extended by the author for an
accelerated monopole charge.Comment: 11 page
Yet Another Model of Soft Gamma Repeaters
We develop a model of SGR in which a supernova leaves planets orbiting a
neutron star in intersecting eccentric orbits. These planets will collide in
years if their orbits are coplanar. Some fragments of debris lose
their angular momentum in the collision and fall onto the neutron star,
producing a SGR. The initial accretion of matter left by the collision with
essentially no angular momentum may produce a superburst like that of March 5,
1979, while debris fragments which later lose their angular momentum produce an
irregular pattern of smaller bursts.Comment: 16pp, Tex, WU-JIK-94-
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