The dynamics of the population imbalance of bosons in a double-well potential is investigated from the point of view of many-body quantum mechanics in the framework of the two-mode model. For small ...initial population imbalances, coherent superpositions of almost equally spaced energy eigenstates lead to Josephson oscillations. The suppression of tunneling at population imbalances beyond a critical value is related to a high concentration of initial state population in the region of the energy spectrum with quasi-degenerate doublets. Negligible coherences among adjacent doublets result in imbalance oscillations with a very small amplitude. For unaccessible long times, however, the system recovers the regime of Josephson oscillations.
Doorway states and the Bose-Hubbard model Salgueiro, A.N.; Lin, Chi-Yong; de Toledo Piza, A.F.R. ...
Nuclear physics. A,
06/2007, Volume:
790, Issue:
1
Journal Article
Peer reviewed
Open access
We apply the doorway method to solve the problem of
N bosons in an optical lattice. This method allows for the inclusion of many-body correlations in a dynamically motivated hierarchical way, ...yielding useful approximations even within subspaces of the full Hilbert space of greatly reduced dimensionality. We calculate some important experimental observables. Excellent qualitative agreement with exact numerical calculations and recent experimental observations is obtained.
Revisiting the Taxonomic Impediment de Carvalho, Marcelo R.; Bockmann, Flávio A.; Amorim, Dalton S. ...
Science (American Association for the Advancement of Science),
01/2005, Volume:
307, Issue:
5708
Journal Article
We show that single and multislit experiments involving matter waves may be constructed to assess dispersively generated correlations between the position and momentum of a single free particle. ...These correlations give rise to position dependent phases which develop dynamically as a result of dispersion and may play an important role in the interference patterns. To the extent that initial transverse coherence is preserved throughout the proposed diffraction setup, such interference patterns are noticeably different from those of a classical dispersion free wave.
Bogoliubov theory for mutually coherent condensates Tommasini, Paolo; de Passos, E. J. V.; de Toledo Piza, A. F. R. ...
Physical review. A, Atomic, molecular, and optical physics,
02/2003, Volume:
67, Issue:
2
Journal Article
We analyze the mean-field equilibrium states of a homogeneous Bose-Einstein condensate of boson particles in different internal states, possibly in the presence of an internal Josephson interaction, ...and we describe the quantum fluctuations by constructing an explicit form of the Bogoliubov transformation that characterizes the quasiparticle excitations of the system. The derivation of the Bogoliubov transformation is based on a simple geometrical picture which leads to a convenient parametrization of the transformation. Our calculations of physical properties, such as depletions and phonon velocities, as well as our discussion of stability, indicate the sense and the extent to which the internal Josephson interaction controls the many-body physics of multicomponent phase coherent matter.
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