36 research outputs found
Collapse and revival in inter-band oscillations of a two-band Bose-Hubbard model
We study the effect of a many-body interaction on inter-band oscillations in
a two-band Bose-Hubbard model with external Stark force. Weak and strong
inter-band oscillations are observed, where the latter arise from a resonant
coupling of the bands. These oscillations collapse and revive due to a weak
two-body interaction between the atoms. Effective models for oscillations in
and out of resonance are introduced that provide predictions for the system's
behaviour, particularly for the time-scales for the collapse and revival of the
resonant inter-band oscillations.Comment: 10 pages, 5 figure
Optical Lattices: Theory
This chapter presents an overview of the properties of a Bose-Einstein
condensate (BEC) trapped in a periodic potential. This system has attracted a
wide interest in the last years, and a few excellent reviews of the field have
already appeared in the literature (see, for instance, [1-3] and references
therein). For this reason, and because of the huge amount of published results,
we do not pretend here to be comprehensive, but we will be content to provide a
flavor of the richness of this subject, together with some useful references.
On the other hand, there are good reasons for our effort. Probably, the most
significant is that BEC in periodic potentials is a truly interdisciplinary
problem, with obvious connections with electrons in crystal lattices, polarons
and photons in optical fibers. Moreover, the BEC experimentalists have reached
such a high level of accuracy to create in the lab, so to speak, paradigmatic
Hamiltonians, which were first introduced as idealized theoretical models to
study, among others, dynamical instabilities or quantum phase transitions.Comment: Chapter 13 in Part VIII: "Optical Lattices" of "Emergent Nonlinear
Phenomena in Bose-Einstein Condensates: Theory and Experiment," edited by P.
G. Kevrekidis, D. J. Frantzeskakis, and R. Carretero-Gonzalez (Springer
Series on Atomic, Optical, and Plasma Physics, 2007) - pages 247-26
Bloch-Zener oscillations
It is well known that a particle in a periodic potential with an additional constant force performs Bloch oscillations. Modulating every second period of the potential, the original Bloch band splits into two subbands. The dynamics of quantum particles shows a coherent superposition of Bloch oscillations and Zener tunneling between the subbands, a Bloch-Zener oscillation. Such a system is modelled by a tight-binding Hamiltonian, a system of two minibands with an easily controllable gap. The dynamics of the system is investigated by using an algebraic ansatz leading to a differential equation of Whittaker-Hill type. It is shown that the parameters of the system can be tuned to generate a periodic reconstruction of the wave packet and thus of the occupation probability. As an application, the construction of a matter wave beam splitter and a Mach-Zehnder interferometer is briefly discussed
Manipulation of matter waves using Bloch and Bloch-Zener oscillations
We present theoretical and numerical results on the dynamics of ultracold atoms in an accelerated single- and double-periodic optical lattice. In the single-periodic potential Bloch oscillations can be used to generate fast directed transport with very little dispersion. The dynamics in the double-periodic system is dominated by Bloch-Zener oscillations, i.e. the interplay of Bloch oscillations and Zener tunneling between the subbands. Apart from directed transport, the latter system permits various interesting applications, such as widely tunable matter wave beam splitters and Mach-Zehnder interferometry. As an application, a method for efficient probing of small nonlinear mean-field interactions is suggested. PACS numbers: 03.65.-w, 03.75.Be, 03.75.Dg, 03.75.LmManipulation of matter waves using Bloch and Bloch-Zener oscillations 2 1
Amplitude modulated Bloch oscillations of photon probability distribution in a cavity–atom system
Beam splitter and combiner based on Bloch oscillation in a spatially modulated waveguide array
The effect of dynamical Bloch oscillations on optical-field-induced current in a wide-gap dielectric
Converting Zitterbewegung oscillation to directed motion
10.1209/0295-5075/96/10004EPL961
Exceptional points in bichromatic Wannier–Stark systems
The resonance spectrum of a tilted periodic quantum system for a bichromatic periodic potential is investigated. For such a bichromatic Wannier–Stark system, exceptional points, degeneracies of the spectrum, can be localized in parameter space by means of an efficient method for computing resonances. Berry phases and Petermann factors are analysed. Finally, the influence of a nonlinearity of the Gross–Pitaevskii type on the resonance crossing scenario is briefly discussed.SCOPUS: ar.jinfo:eu-repo/semantics/publishe