3,673 research outputs found
Soliton trains in Bose-Fermi mixtures
We theoretically consider the formation of bright solitons in a mixture of
Bose and Fermi degenerate gases. While we assume the forces between atoms in a
pure Bose component to be effectively repulsive, their character can be changed
from repulsive to attractive in the presence of fermions provided the Bose and
Fermi gases attract each other strongly enough. In such a regime the Bose
component becomes a gas of effectively attractive atoms. Hence, generating
bright solitons in the bosonic gas is possible. Indeed, after a sudden increase
of the strength of attraction between bosons and fermions (realized by using a
Feshbach resonance technique or by firm radial squeezing of both samples)
soliton trains appear in the Bose-Fermi mixture.Comment: 4 pages, 4 figure
Coulomb blockade and Bloch oscillations in superconducting Ti nanowires
Quantum fluctuations in quasi-one-dimensional superconducting channels
leading to spontaneous changes of the phase of the order parameter by ,
alternatively called quantum phase slips (QPS), manifest themselves as the
finite resistance well below the critical temperature of thin superconducting
nanowires and the suppression of persistent currents in tiny superconducting
nanorings. Here we report the experimental evidence that in a current-biased
superconducting nanowire the same QPS process is responsible for the insulating
state -- the Coulomb blockade. When exposed to RF radiation, the internal Bloch
oscillations can be synchronized with the external RF drive leading to
formation of quantized current steps on the I-V characteristic. The effects
originate from the fundamental quantum duality of a Josephson junction and a
superconducting nanowire governed by QPS -- the QPS junction (QPSJ).Comment: 5 pages, 4 figure
Quantum Many-Body Dynamics of Dark Solitons in Optical Lattices
We present a fully quantum many-body treatment of dark solitons formed by
ultracold bosonic atoms in one-dimensional optical lattices. Using
time-evolving block decimation to simulate the single-band Bose-Hubbard
Hamiltonian, we consider the quantum dynamics of density and phase engineered
dark solitons as well as the quantum evolution of mean-field dark solitons
injected into the quantum model. The former approach directly models how one
may create quantum entangled dark solitons in experiment. While we have already
presented results regarding the latter approach elsewhere [Phys. Rev. Lett.
{\bf 103}, 140403 (2009)], we expand upon those results in this work. In both
cases, quantum fluctuations cause the dark soliton to fill in and may induce an
inelasticity in soliton-soliton collisions. Comparisons are made to the
Bogoliubov theory which predicts depletion into an anomalous mode that fills in
the soliton. Our many-body treatment allows us to go beyond the Bogoliubov
approximation and calculate explicitly the dynamics of the system's natural
orbitals.Comment: 14 pages, 11 figures -- v3 has only minor changes from v2 -- this is
the print versio
Stabilization of a light bullet in a layered Kerr medium with sign-changing nonlinearity
Using the numerical solution of the nonlinear Schr\"odinger equation and a
variational method it is shown that (3+1)-dimensional spatiotemporal optical
solitons, known as light bullets, can be stabilized in a layered Kerr medium
with sign-changing nonlinearity along the propagation direction.Comment: 4 pages, 3 PS figure
Stabilization of bright solitons and vortex solitons in a trapless three-dimensional Bose-Einstein condensate by temporal modulation of the scattering length
Using variational and numerical solutions of the mean-field Gross-Pitaevskii
equation we show that a bright soliton can be stabilized in a trapless
three-dimensional attractive Bose-Einstein condensate (BEC) by a rapid periodic
temporal modulation of scattering length alone by using a Feshbach resonance.
This scheme also stabilizes a rotating vortex soliton in two dimensions. Apart
from possible experimental application in BEC, the present study suggests that
the spatiotemporal solitons of nonlinear optics in three dimensions can also be
stabilized in a layered Kerr medium with sign-changing nonlinearity along the
propagation direction.Comment: 6 pages, 7 PS figure
Modulated wavepackets associated with longitudinal dust grain oscillations in a dusty plasma crystal
The nonlinear amplitude modulation of longitudinal dust lattice waves (LDLWs)
propagating in a dusty plasma crystal is investigated in a continuum
approximation. It is shown that long wavelength LDLWs are modulationally
stable, while shorter wavelengths may be unstable. The possibility for the
formation and propagation of different envelope localized excitations is
discussed. It is shown that the total grain displacement bears a (weak)
constant displacement (zeroth harmonic mode), due to the asymmetric form of the
nonlinear interaction potential. The existence of asymmetric envelope localized
modes is predicted. The types and characteristics of these coherent nonlinear
structures are discussed.Comment: 18 pages, 7 figures, to appear in Physics of Plasma
Combination of inverse spectral transform method and method of characteristics: deformed Pohlmeyer equation
We apply a version of the dressing method to a system of four dimensional
nonlinear Partial Differential Equations (PDEs), which contains both Pohlmeyer
equation (i.e. nonlinear PDE integrable by the Inverse Spectral Transform
Method) and nonlinear matrix PDE integrable by the method of characteristics as
particular reductions. Some other reductions are suggested.Comment: 12 page
Stabilization of a (3+1)D soliton in a Kerr medium by a rapidly oscillating dispersion coefficient
Using the numerical solution of the nonlinear Schroedinger equation and a
variational method it is shown that (3+1)-dimensional spatiotemporal optical
solitons can be stabilized by a rapidly oscillating dispersion coefficient in a
Kerr medium with cubic nonlinearity. This has immediate consequence in
generating dispersion-managed robust optical soliton in communication as well
as possible stabilized Bose-Einstein condensates in periodic optical-lattice
potential via an effective-mass formulation. We also critically compare the
present stabilization with that obtained by a rapid sinusoidal oscillation of
the Kerr nonlinearity parameter.Comment: 6 pages, 6 ps figures, New figure 4 added, Physical Review
Integrated Lax Formalism for PCM
By solving the first-order algebraic field equations which arise in the dual
formulation of the D=2 principal chiral model (PCM) we construct an integrated
Lax formalism built explicitly on the dual fields of the model rather than the
currents. The Lagrangian of the dual scalar field theory is also constructed.
Furthermore we present the first-order PDE system for an exponential
parametrization of the solutions and discuss the Frobenious integrability of
this system.Comment: 24 page
- …