19,963 research outputs found
Effective generation of Ising interaction and cluster states in coupled microcavities
We propose a scheme for realizing the Ising spin-spin interaction and atomic
cluster states utilizing trapped atoms in coupled microcavities. It is shown
that the atoms can interact with each other via the exchange of virtual photons
of the cavities. Through suitably tuning the parameters, an effective Ising
spin-spin interaction can be generated in this optical system, which is used to
produce the cluster states. This scheme does not need the preparation of
initial states of atoms and cavity modes, and is insensitive to cavity decay.Comment: 11pages, 2 figures, Revtex
Coherent Manipulation of Quantum Delta-kicked Dynamics: Faster-than-classical Anomalous Diffusion
Large transporting regular islands are found in the classical phase space of
a modified kicked rotor system in which the kicking potential is reversed after
every two kicks. The corresponding quantum system, for a variety of system
parameters and over long time scales, is shown to display energy absorption
that is significantly faster than that associated with the underlying classical
anomalous diffusion. The results are of interest to both areas of quantum chaos
and quantum control.Comment: 6 pages, 4 figures, to appear in Physical Review
Temperature Dependent Empirical Pseudopotential Theory For Self-Assembled Quantum Dots
We develop a temperature dependent empirical pseudopotential theory to study
the electronic and optical properties of self-assembled quantum dots (QDs) at
finite temperature. The theory takes the effects of both lattice expansion and
lattice vibration into account. We apply the theory to the InAs/GaAs QDs. For
the unstrained InAs/GaAs heterostructure, the conduction band offset increases
whereas the valence band offset decreases with increasing of the temperature,
and there is a type-I to type-II transition at approximately 135 K. Yet, for
InAs/GaAs QDs, the holes are still localized in the QDs even at room
temperature, because the large lattice mismatch between InAs and GaAs greatly
enhances the valence band offset. The single particle energy levels in the QDs
show strong temperature dependence due to the change of confinement potentials.
Because of the changes of the band offsets, the electron wave functions
confined in QDs increase by about 1 - 5%, whereas the hole wave functions
decrease by about 30 - 40% when the temperature increases from 0 to 300 K. The
calculated recombination energies of exciton, biexciton and charged excitons
show red shifts with increasing of the temperature, which are in excellent
agreement with available experimental data
Phase Control of Nonadiabaticity-induced Quantum Chaos in An Optical Lattice
The qualitative nature (i.e. integrable vs. chaotic) of the translational
dynamics of a three-level atom in an optical lattice is shown to be
controllable by varying the relative laser phase of two standing wave lasers.
Control is explained in terms of the nonadiabatic transition between optical
potentials and the corresponding regular to chaotic transition in mixed
classical-quantum dynamics. The results are of interest to both areas of
coherent control and quantum chaos.Comment: 3 figures, 4 pages, to appear in Physical Review Letter
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