7,254 research outputs found
Anderson localization in the quintic nonlinear Schr\"odinger equation
In the present paper we consider the quintic defocusing nonlinear
Schr\"odinger equation in presence of a disordered random potential and we
analyze the effects of the quintic nonlinearity on the Anderson localization of
the solution. The main result shows that Anderson localization requires a
cutoff on the value of the parameter which controls the quintic nonlinearity,
with the cutoff depending on the amplitude of the random potential.Comment: 4 pages, 7 figure
Entanglement of formation for qubit-qudit system using partition of qudit sytem into a set of qubit system
Gerjuoy [Phys. Rev. A 67, 052308 (2003)] has derived a closed- form lower
bound for the entanglement of formation of a mixed qubit-qudit system (qudit
system has d levels with d>=3. In this paper, inspired by Gerjuoy's method, we
propose a scheme that partitions a qubit-qudit system into d(d-1)/2 qubit-qubit
systems, which can be treated by all known methods pertinent to qubit-qubit
system. The method is demonstrated by a qubit-qudit system (The levels of qudit
are d=3 and d=5, respectively
Dark soliton in quasi-one-dimensional Bose-Einstein condensates with a Gaussian trap
In this paper we study dark solitons in quasi-one-dimensional Bose-Einstein
condensates (BECs) in presence of an anharmonic external potential. The
theoretical model is based on the Mu\~noz-Mateo and Delgado (MMD) equation that
describes cigar-shaped BECs with repulsive interatomic interactions. Since MMD
equation presents a nonpolynomial form, the soliton-sound recombination cannot
display the same pattern presented in the cubic model. We perform numerical
simulations to compare both cases.Comment: 7 pages, 5 figure
Unidimensional reduction of the 3D Gross-Pitaevskii equation with two- and three-body interactions
We deal with the three-dimensional Gross-Pitaevskii equation, which is used
to describe a cloud of dilute bosonic atoms that interact under competing two-
and three-body scattering potentials. We study the case where the cloud of
atoms is strongly confined in two spatial dimensions, allowing us to build an
unidimensional nonlinear equation, controlled by the nonlinearities and the
confining potentials that trap the system along the longitudinal coordinate. We
focus attention on specific limits, dictated by the cubic and quintic
coefficients, and we implement numerical simulations to help us to quantify the
validity of the procedure.Comment: 6 pages, 4 figures; version to appear in PR
Modulation of breathers in cigar-shaped Bose-Einstein condensates
We present new solutions to the nonautonomous nonlinear Schroedinger equation
that may be realized through convenient manipulation of Bose-Einstein
condensates. The procedure is based on the modulation of breathers through an
analytical study of the one-dimensional Gross-Pitaevskii equation, which is
known to offer a good theoretical model to describe quasi-one-dimensional
cigar-shaped condensates. Using a specific Ansatz, we transform the
nonautonomous nonlinear equation into an autonomous one, which engenders
composed states corresponding to solutions localized in space, with an
oscillating behavior in time. Numerical simulations confirm stability of the
breathers against random perturbation on the input profile of the solutions
Generation of arbitrary Fock states via resonant interactions in cavity QED
We propose a scheme to generate arbitrary Fock states |N> in a cavity QED
using N resonant Rydberg atoms. The atom-field interaction times are controlled
via Stark-shifts adjusted in a way that each atom transfers a photon to the
cavity, turning atomic detections useless. Fluctuations affecting the control
of the atom-field interactions are also considered.Comment: 3 pages, 2 figures
Controlled teleportation via photonic Faraday rotations in low-Q cavities
This paper presents feasible experimental schemes to realize controlled
teleportation protocols via photonic Faraday rotations in low-Q cavities. The
schemes deal with controlled teleportation of superposition states and
two-particle entanglement of atomic states. The information is encoded in
three-level atoms in a lambda configuration trapped inside coupled cavities by
optical fibers. Also, we estimate the success probability and the current
feasibility of the schemes.Comment: 16 pages, 7 figures, 6 table
Splitting of quantum information in traveling wave fields using only linear optical elements
In this brief report we present a feasible scheme to split quantum
information in the realm of traveling waves. An oversimplified scheme is also
proposed for the generation of a class of W states useful for perfect
teleportation and superdense coding. The scheme employs only linear optical
elements as beam splitters and phase shifters, in addition to photon counters
and one-photon sources. It is shown that splitting of quantum information with
high fidelity is possible even including inefficiency of the detectors and
photoabsorption of the beam splitters.Comment: 4 pages, 6 figure
A proposal to implement a quantum delayed choice experiment assisted by a cavity QED
We propose a scheme feasible with current technology to implement a quantum
delayed-choice experiment in the realm of cavity QED. Our scheme uses two-level
atoms interacting on and off resonantly with a single mode of a high Q cavity.
At the end of the protocol, the state of the cavity returns to its ground
state, allowing new sequential operations. The particle and wave behavior,
which are verified in a single experimental setup, are postselected after the
atomic states are selectively detected.Comment: 3 pages, 3 figures. arXiv admin note: text overlap with
arXiv:1208.0802 by other author
Bright solitons from the nonpolynomial Schr\"odinger equation with inhomogeneous defocusing nonlinearities
Extending the recent work on models with spatially nonuniform nonlinearities,
we study bright solitons generated by the nonpolynomial self-defocusing (SDF)
nonlinearity in the framework of the one-dimensional (1D) Mu\~{n}oz-Mateo -
Delgado (MM-D) equation (the 1D reduction of the Gross-Pitaevskii equation with
the SDF nonlinearity), with the local strength of the nonlinearity growing at
any rate faster than |x| at large values of coordinate x. We produce numerical
solutions and analytical ones, obtained by means of the Thomas-Fermi
approximation (TFA), for nodeless ground states, and for excited modes with 1,
2, 3, and 4 nodes, in two versions of the model, with the steep (exponential)
and mild (algebraic) nonlinear-modulation profiles. In both cases, the ground
states and the single-node ones are completely stable, while the stability of
the higher-order modes depends on their norm (in the case of the algebraic
modulation, they are fully unstable). Unstable states spontaneously evolve into
their stable lower-order counterparts.Comment: 5 pages, 6 figures, (Physical Review E, in press
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