17 research outputs found
On the information entropy of matter-waves in quasi-disorder potentials
We consider ultracold Bose gases in quasi-random potentials and quantify
localization of matter waves by means of Shannon information entropy. We
explicitly examine the role of quasi-random potentials in producing localized
states in the linear and nonlinear regimes. It is seen that the information
entropic-based approach can be more useful to quantify localization of
different types of states observed in Bose-Einstein condensates.Comment: 8 pages, 6 figure
Josephson-type oscillations in spin-orbit coupled Bose-Einstein condensates with nonlinear optical lattices
We consider spin orbit coupled Bose Einstein Condensate in presence of linear
and nonlinear optical lattices within the framework of quasi-one-dimensional
Gross-Pitaevskii equation. Based on a variational approach, we find an
effective potential and show that the atomic population imbalance between these
states executes Josephson-type oscillation. We find that the oscillation
amplitude depends sensitively on center of mass motion of the coupled system.
Maximum value of the oscillation amplitude remains constant if the center of
mass is at rest. It oscillates if the center of mass moving in optical lattice.
We find that a nonlinear optical lattice induces an additional phase and thus
influences the JT oscillation.Comment: 5 pages, 5 Figure
Typical observables in a two-mode Bose system
A class of k-particle observables in a two-mode system of Bose particles is
characterized by typicality: if the state of the system is sampled out of a
suitable ensemble, an experimental measurement of that observable yields
(almost) always the same result. We investigate the general features of typical
observables, the criteria to determine typicality and finally focus on the case
of density correlation functions, which are related to spatial distribution of
particles and interference.Comment: 8 pages, 1 figur
Displaced dynamics of binary mixtures in linear and nonlinear optical lattices
The dynamical behavior of matter wave solitons of two-component Bose-Einstein
condensates (BEC) in combined linear and nonlinear optical lattices (OLs) is
investigated. In particular, the dependence of the frequency of the oscillating
dynamics resulting from initially slightly displaced components is investigated
both analytically, by means of a variational effective potential approach for
the reduced collective coordinate dynamics of the soliton, and numerically, by
direct integrations of the mean field equations of the BEC mixture. We show
that for small initial displacements binary solitons can be viewed as point
masses connected by elastic springs of strengths related to the amplitude of
the OL and to the intra and inter-species interactions. Analytical expressions
of symmetric and anti-symmetric mode frequencies, are derived and occurrence of
beatings phenomena in the displaced dynamics is predicted. These expressions
are shown to give a very good estimation of the oscillation frequencies for
different values of the intra-species interatomic scattering length, as
confirmed by direct numerical integrations of the mean field Gross-Pitaevskii
equations (GPE) of the mixture. The possibility to use displaced dynamics for
indirect measurements of BEC mixture characteristics such as number of atoms
and interatomic interactions is also suggested.Comment: 8 pages, 21 figure
Split and overlapped binary solitons in optical lattices
We analyze the energetic and dynamical properties of bright-bright (BB)
soliton pairs in a binary mixture of Bose-Einstein condensates subjected to the
action of a combined optical lattice, acting as an external potential for the
first species, while modulating the intraspecies coupling constant of the
second. In particular, we use a variational approach and direct numerical
integrations to investigate the existence and stability of BB solitons in which
the two species are either spatially separated (split soliton) or located at
the same optical lattice site (overlapped soliton). The dependence of these
solitons on the interspecies interaction parameter is explicitly investigated.
For repulsive interspecies interaction we show the existence of a series of
critical values at which transitions from an initially overlapped soliton to
split solitons occur. For attractive interspecies interaction only single
direct transitions from split to overlapped BB solitons are found. The
possibility to use split solitons for indirect measurements of scattering
lengths is also suggested.Comment: 9 pages, 10 figure