1,300 research outputs found
Simulation of quantum dynamics with quantum optical systems
We propose the use of quantum optical systems to perform universal simulation
of quantum dynamics. Two specific implementations that require present
technology are put forward for illustrative purposes. The first scheme consists
of neutral atoms stored in optical lattices, while the second scheme consists
of ions stored in an array of micro--traps. Each atom (ion) supports a
two--level system, on which local unitary operations can be performed through a
laser beam. A raw interaction between neighboring two--level systems is
achieved by conditionally displacing the corresponding atoms (ions). Then,
average Hamiltonian techniques are used to achieve evolutions in time according
to a large class of Hamiltonians.Comment: 14 pages, 6 figure
High Density QCD, Saturation and Diffractive DIS
We review a consistent description of the fusion and saturation of partons in
the Lorentz-contracted ultrarelativistic nuclei in terms of a nuclear
attenuation of color dipole states of the photon and collective
Weizs\"acker-Williams (WW) gluon structure function of a nucleus. Diffractive
DIS provides a basis for the definition of the WW nuclear glue. The point that
all observables for DIS off nuclei are uniquely calculable in terms of the
nuclear WW glue amounts to a new form of factorization in the saturation
regime.Comment: 13 pages, 4 figures, Invited talk at NATO Advanced Research Workshop
On Diffraction 2002, 31 Aug - 6 Sep 2002, Alushta, Ukrain
Diffractive Hard Dijets and Nuclear Parton Distributions
Diffraction plays an exceptional role in DIS off heavy nuclei. First,
diffraction into hard dijets is an unique probe of the unintegrated glue in the
target. Second, because diffraction makes 50 per cent of total DIS off a heavy
target, understanding diffraction in a saturation regime is crucial for a
definition of saturated nuclear parton densities. After brief comments on the
Nikolaev-Zakharov (NZ) pomeron-splitting mechanism for diffractive hard dijet
production, I review an extension of the Nikolaev-Schafer-Schwiete (NSS)
analysis of diffractive dijet production off nuclei to the definition of
nuclear partons in the saturation regime. I emphasize the importance of
intranuclear final state interactions for the parton momentum distributions.Comment: 9 pages, 2 figures, to be published in Proceedings of the Workshop on
Exclusive Processes at High Momentum Transfer, Jefferson Lab, May 15-18,
2002. Typos corrected, discussion of the results extende
Spin-Dependent Hubbard Model and a Quantum Phase Transition in Cold Atoms
We describe an experimental protocol for introducing spin-dependent lattice
structure in a cold atomic fermi gas using lasers. It can be used to realize
Hubbard models whose hopping parameters depend on spin and whose interaction
strength can be controlled with an external magnetic field. We suggest that
exotic superfluidities will arise in this framework. An especially interesting
possibility is a class of states that support coexisting superfluid and normal
components, even at zero temperature. The quantity of normal component varies
with external parameters. We discuss some aspects of the quantum phase
transition that arises at the point where it vanishes.Comment: 9 pages, 7 figures; added/corrected references in [11] and [44
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