1,198 research outputs found
Energy dissipation in wave propagation in general relativistic plasma
Based on a recent communication by the present authors the question of energy
dissipation in magneto hydrodynamical waves in an inflating background in
general relativity is examined. It is found that the expanding background
introduces a sort of dragging force on the propagating wave such that unlike
the Newtonnian case energy gets dissipated as it progresses. This loss in
energy having no special relativistic analogue is, however, not mechanical in
nature as in elastic wave. It is also found that the energy loss is model
dependent and also depends on the number of dimensions.Comment: 12 page
Quintessential Phenomena in Higher Dimensional Space Time
The higher dimensional cosmology provides a natural setting to treat, at a
classical level, the cosmological effects of vacuum energy. Here we discuss two
situations where starting with an ordinary matter field without any equation of
state we end up with a Chaplygin type of gas apparently as a consequence of
extra dimensions. In the second case we study the quintessential phenomena in
higher dimensional spacetime with the help of a Chaplygin type of matter field.
The first case suffers from the disqualification that no dimensional reduction
occurs, which is, however, rectified in the second case. Both the models show
the sought after feature of occurrence of \emph{flip} in the rate of expansion.
It is observed that with the increase of dimensions the occurrence of
\emph{flip} is delayed for both the models, more in line with current
observational demands. Interestingly we see that depending on some initial
conditions our model admits QCDM, CDM and also Phantom like evolution
within a unified framework. Our solutions are general in nature in the sense
that when the extra dimensions are switched off the known 4D model is
recovered.Comment: 17 Pages, 7 figure
Controlled transportation of mesoscopic particles by enhanced spin orbit interaction of light in an optical trap
We study the effects of the spin orbit interaction (SOI) of light in an
optical trap and show that the propagation of the tightly focused trapping beam
in a stratified medium can lead to significantly enhanced SOI. For a plane
polarized incident beam the SOI manifests itself by giving rise to a strong
anisotropic linear diattenuation effect which produces polarization-dependent
off-axis high intensity side lobes near the focal plane of the trap. Single
micron-sized asymmetric particles can be trapped in the side lobes, and
transported over circular paths by a rotation of the plane of input
polarization. We demonstrate such controlled motion on single pea-pod shaped
single soft oxometalate (SOM) particles of dimension around m
over lengths up to 15 m . The observed effects are supported by
calculations of the intensity profiles based on a variation of the Debye-Wolf
approach. The enhanced SOI could thus be used as a generic means of
transporting mesoscopic asymmetric particles in an optical trap without the use
of complex optical beams or changing the alignment of the beam into the trap.Comment: 9 pages, 7 figure
Generation of entangled channels for perfect teleportation channels using multi-electron quantum dots
In this work we have proposed a scheme for generating qubit entangled
states which can teleport an unknown state perfectly. By switching on the
exchange interaction () between the qubits one can get the desired states
periodically. A multi electron quantum dot can be a possible realization for
generating such qubit states with high fidelity. In the limit of , there exists a unique time where the
Hamiltonian dynamics gives the qubit state that can assist perfect
teleportation. We have also discussed the effect of the nuclear spin
environment on the fidelity of teleportation for a general qubit entangled
channel.Comment: 6 pages, 3 figure
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