81 research outputs found
Off-axis vortex beam propagation through classical optical system in terms of Kummer confluent hypergeometric function
The analytical solution for the propagation of the laser beam with optical
vortex through the system of lenses is presented. The optical vortex is
introduced into the laser beam (described as Gaussian beam) by spiral phase
plate. The solution is general as it holds for the optical vortex of any
integer topological charge, the off-axis position of the spiral phase plate and
any number of lenses. Some intriguing conclusions are discussed. The higher
order vortices are unstable and split under small phase or amplitude
disturbance. Nevertheless, we have shown that off-axis higher order vortices
are stable during the propagation through the set of lenses described in
paraxial approximation, which is untypical behavior. The vortex trajectory
registered at image plane due to spiral phase plate shift behaves like a rigid
body. We have introduced a new factor which in our beam plays the same role as
Gouy phase in pure Gaussian beam.Comment: 28 pages, 8 figure
Polygonal micro-whirlpools induced in ferrofluids
We report on the observation of the polygonal whirlpools in the thin layer of
ferrofluid under illumination with a laser beam carrying optical vortex and in
the presence of a vertical magnetic field. This kind of structures have
attracted attention after discovering a hexagonal storm in Saturns atmosphere.
Our polygonal whirlpools were created in a closed system (no free surfaces) in
micro scale (whirlpool diameter less than 20 micrometers) by the use of
holographic optical tweezers. The polygonal shape was changed by varying the
magnetic field strength or value of the optical vortex topological charge
Local Purity Distillation in Quantum Systems: Exploring the Complementarity Between Purity and Entanglement
Quantum thermodynamics and quantum entanglement represent two pivotal quantum
resource theories with significant relevance in quantum information science.
Despite their importance, the intricate relationship between these two theories
is still not fully understood. Here, we delve into the interplay between
entanglement and thermodynamics, particularly in the context of local cooling
processes. We introduce and develop the framework of Gibbs-preserving local
operations and classical communication. Within this framework, we explore
strategies enabling remote parties to effectively cool their local systems to
the ground state. Our analysis is centered on scenarios where only a single
copy of a quantum state is accessible, with the ideal performance defined by
the highest possible fidelity to the ground state achievable under these
constraints. We focus on systems with fully degenerate local Hamiltonians,
where local cooling aligns with the extraction of local purity. In this
context, we establish a powerful link between the efficiency of local purity
extraction and the degree of entanglement present in the system, a concept we
define as purity-entanglement complementarity. Moreover, we demonstrate that in
many pertinent scenarios, the optimal performance can be precisely determined
through semidefinite programming techniques. Our findings open doors to various
practical applications, including techniques for entanglement detection and
estimation. We demonstrate this by evaluating the amount of entanglement for a
class of bound entangled states.Comment: 5+4 pages, 4 figure
On the speed of a test particle inside the Schwarzschild event horizon and other kinds of black holes
We present the results of an investigation of the speed of a radially infalling test particle crossing the event horizon of a black hole within a Schwarzschild spacetime. One finds that the speed as measured by a special class of observers, at rest outside the horizon and static inside the horizon, increases when the test particle approaches the horizon but decreases inside the horizon. The corresponding situation regarding black holes possessing both outer and inner horizons is also briefly discussed
Internal flows and energy circulation in light beams
We review optical phenomena associated with the internal energy
redistribution which accompany propagation and transformations of monochromatic
light fields in homogeneous media. The total energy flow (linear-momentum
density, Poynting vector) can be divided into spin part associated with the
polarization and orbital part associated with the spatial inhomogeneity. We
give general description of the internal flows in the coordinate and momentum
(angular spectrum) representations for both nonparaxial and paraxial fields.
This enables one to determine local densities and integral values of the spin
and orbital angular momenta of the field. We analyse patterns of the internal
flows in standard beam models (Gaussian, Laguerre-Gaussian, flat-top beam,
etc.), which provide an insightful picture of the energy transport. The
emphasize is made to the singular points of the flow fields. We describe the
spin-orbit and orbit-orbit interactions in the processes of beam focusing and
symmetry breakdown. Finally, we consider how the energy flows manifest
themselves in the mechanical action on probing particles and in the
transformations of a propagating beam subjected to a transverse perturbation.Comment: 50 pages, 21 figures, 173 references. This is the final version of
the manuscript (v1) modified in accord to the referee's remarks and with
allowance for the recent development. The main changes are: additional
discussion of the energy flows in Bessel beams (section 4.1), a lot of new
references are added and the Conclusion is shortened and made more accurat
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