12 research outputs found
Low-energy behavior of strongly interacting bosons on a flat-band lattice above the critical filling factor
Quantum spin transistor with a Heisenberg spin chain
We propose and analyze a scheme for conditional state transfer in a
Heisenberg spin chain which realizes a quantum spin transistor. In our
scheme, the absence or presence of a control spin excitation in the central
gate part of the spin chain results in either perfect transfer of an arbitrary
state of a target spin between the weakly coupled input and output ports, or
its complete blockade at the input port. We also present a possible realization
of the corresponding spin chain with a one-dimensional ensemble of cold atoms
with strong contact interactions.Comment: 36 pages, 3 figures, including supplements. See journal reference
below for refereed and revised versio
Experimental observation of anomalous topological edge modes in a slowly-driven photonic lattice
Topological quantum matter can be realized by subjecting engineered systems to time-periodic modulations. In analogy with static systems, periodically driven quantum matter can be topologically classified by topological invariants, whose non-zero value guarantees the presence of robust edge modes. In the high-frequency limit of the drive, topology is described by standard topological invariants, such as Chern numbers. Away from this limit, these topological numbers become irrelevant, and novel topological invariants must be introduced to capture topological edge transport. The corresponding edge modes were coined anomalous topological edge modes, to highlight their intriguing origin. Here we demonstrate the experimental observation of these topological edge modes in a 2D photonic lattice, where these propagating edge states are shown to coexist with a quasi-localized bulk. Our work opens an exciting route for the exploration of topological physics in time-modulated systems operating away from the high-frequency regime
Few quantum particles on one dimensional lattices
Der aktuelle experimentelle Fortschritt bei der Manipulation ultrakalter Atome mit Licht löst gegenwärtig ein großes Interesse an der Physik entarteter Quantengase und der niederenergetischen Streuung weniger Teilchen aus. Insbesondere ist es möglich, nahezu perfekte periodische Potenziale sogenannte optische Gitter, zu generieren. Die Untersuchung des Verhaltens weniger Quantenteilchen in einem eindimensionalen Gitter ist Thema dieser Arbeit. Der Großteil der Ergebnisse ist im Rahmen der tight-binding-Näherung erhalten worden, welche eine exakt numerische oder analytische Behandlung ermöglicht. Für das Zwei-Körper Problem werden theoretische Methoden entwickelt, um stationäre Streuzustände und gebundene Zustände zu berechnen, und diese werden verallgemeinert, um exakte Ergebnisse für beliebige Wechselwirkungen and Teilchenstatistiken zu erhalten. Der Quantentransport von einem und zwei Teilchen wird auch berücksichtigt. Das Problem der Bindung und Streuung dreier identischer Bosonen wird eingehend betrachtet, wobei neuartige Typen von gebundenen Zuständen entdeckt wurden. Schließlich werden andere Gittersysteme studiert, indem Methoden vorgestellt werden, die mit den für das Zwei-Körper Problem entwickelten Methoden eng verwandt sind.There is currently a great interest in the physics of degenerate quantum gases and low-energy few-body scattering due to the recent experimental advances in manipulation of ultracold atoms by light. In particular, almost perfect periodic potentials, called optical lattices, can be generated. The physics of few quantum particles on a one-dimensional lattice is the topic of this thesis. Most of the results are obtained in the tight-binding approximation, which is amenable to exact numerical or analytical treatment. For the two-body problem, theoretical methods for calculating the stationary scattering and bound states are developed, and are generalized to obtain exact results for arbitrary interactions and particle statistics. Quantum transport of one and two particles is also considered. The problem of binding and scattering of three identical bosons is studied in detail, finding novel types of bound states. Finally, other lattice systems are studied by introducing methods closely connected with the methods developed for the two-body problem
Scattering resonances and two-particle bound states of the extended Hubbard model
We present a complete derivation of two-particle states of the
one-dimensional extended Hubbard model involving attractive or repulsive
on-site and nearest-neighbour interactions. We find that this system possesses
scattering resonances and two families of energy-dependent interaction-bound
states which are not present in the Hubbard model with the on-site interaction
alone.Comment: 4 pages, 4 figure
Quantum dynamics of one and two bosonic atoms in a combined tight-binding periodic and weak parabolic potential
Strongly interacting bosonic particles in a tight-binding periodic potential
superimposed by a weak parabolic trap is a paradigm for many cold atom
experiments. Here, after revisiting the single particle problem, we study
interaction-bound dimers of bosonic atoms in the combined lattice and parabolic
potential. We consider both repulsively- and attractively-bound dimers and find
pronounced differences in their behaviour. We identify conditions under which
attractive and repulsive dimers exhibit analogous dynamics. Our studies reveal
that coherent transport and periodic oscillations of appropriately prepared
one- and two-atom wavepackets can be achieved, which may facilitate information
transfer in optical lattice based quantum computation schemes.Comment: 6 pages, 6 figure
Deaf-Mute Pelican (1882-1894) and The Louisiana Pelican (1894-1900 & 1914-1915)
v. : ill., 25 cm.A "Little Paper Family" publicationSubmitted by Seung Hahn ([email protected]) on 2013-06-10T17:19:47Z
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Previous issue date: 1971-1
On the Josephson effect in a Bose–Einstein condensate subject to a density-dependent gauge potential
We investigate the coherent dynamics of a Bose-Einstein condensate in a
double well, subject to a density dependent gauge potential. Further, we derive
the nonlinear Josephson equations that allow us to understand the many-body
system in terms of a classical Hamiltonian that describes the motion of a
nonrigid pendulum with an initial angular offset. Finally we analyze the
phase-space trajectories of the system, and describe how the self-trapping is
affected by the presence of an interacting gauge potential.Comment: 6 pages, 2 figure