282,161 research outputs found
Orbital motion effects in astrometric microlensing
We investigate lens orbital motion in astrometric microlensing and its
detectability. In microlensing events, the light centroid shift in the source
trajectory (the astrometric trajectory) falls off much more slowly than the
light amplification as the source distance from the lens position increases. As
a result, perturbations developed with time such as lens orbital motion can
make considerable deviations in astrometric trajectories. The rotation of the
source trajectory due to lens orbital motion produces a more detectable
astrometric deviation because the astrometric cross-section is much larger than
the photometric one. Among binary microlensing events with detectable
astrometric trajectories, those with stellar-mass black holes have most likely
detectable astrometric signatures of orbital motion. Detecting lens orbital
motion in their astrometric trajectories helps to discover further secondary
components around the primary even without any photometric binarity signature
as well as resolve close/wide degeneracy. For these binary microlensing events,
we evaluate the efficiency of detecting orbital motion in astrometric
trajectories and photometric light curves by performing Monte Carlo simulation.
We conclude that astrometric efficiency is 87.3 per cent whereas the
photometric efficiency is 48.2 per cent.Comment: 9 pages, 8 figures, accepted for publication in MNRA
Quantum trajectories for Brownian motion
We present the stochastic Schroedinger equation for the dynamics of a quantum
particle coupled to a high temperature environment and apply it the dynamics of
a driven, damped, nonlinear quantum oscillator. Apart from an initial slip on
the environmental memory time scale, in the mean, our result recovers the
solution of the known non-Lindblad quantum Brownian motion master equation. A
remarkable feature of our approach is its localization property: individual
quantum trajectories remain localized wave packets for all times, even for the
classically chaotic system considered here, the localization being stronger the
smaller .Comment: 4 pages, 3 eps figure
Two charges on plane in a magnetic field: special trajectories
A classical mechanics of two Coulomb charges on a plane and
subject to a constant magnetic field perpendicular to a plane is
considered. Special "superintegrable" trajectories (circular and linear) for
which the distance between charges remains unchanged are indicated as well as
their respectful constants of motion. The number of the independent constants
of motion for special trajectories is larger for generic ones. A classification
of pairs of charges for which special trajectories occur is given. The special
trajectories for three particular cases of two electrons, (electron -
positron), (electron - -particle) are described explicitly.Comment: 22 pages, 5 figure
Coherent States and Modified de Broglie-Bohm Complex Quantum Trajectories
This paper examines the nature of classical correspondence in the case of
coherent states at the level of quantum trajectories. We first show that for a
harmonic oscillator, the coherent state complex quantum trajectories and the
complex classical trajectories are identical to each other. This congruence in
the complex plane, not restricted to high quantum numbers alone, illustrates
that the harmonic oscillator in a coherent state executes classical motion. The
quantum trajectories are those conceived in a modified de Broglie-Bohm scheme
and we note that identical classical and quantum trajectories for coherent
states are obtained only in the present approach. The study is extended to
Gazeau-Klauder and SUSY quantum mechanics-based coherent states of a particle
in an infinite potential well and that in a symmetric Poschl-Teller (PT)
potential by solving for the trajectories numerically. For the coherent state
of the infinite potential well, almost identical classical and quantum
trajectories are obtained whereas for the PT potential, though classical
trajectories are not regained, a periodic motion results as t --> \infty.Comment: More example
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