14,020 research outputs found
Growth on the border or bordering on growth ?
Economic development ; Economic conditions - Texas
Influence of qubit displacements on quantum logic operations in a silicon-based quantum computer with constant interaction
The errors caused by qubit displacements from their prescribed locations in
an ensemble of spin chains are estimated analytically and calculated
numerically for a quantum computer based on phosphorus donors in silicon. We
show that it is possible to polarize (initialize) the nuclear spins even with
displaced qubits by using Controlled NOT gates between the electron and nuclear
spins of the same phosphorus atom. However, a Controlled NOT gate between the
displaced electron spins is implemented with large error because of the
exponential dependence of exchange interaction constant on the distance between
the qubits. If quantum computation is implemented on an ensemble of many spin
chains, the errors can be small if the number of chains with displaced qubits
is small
Double-Slit Interferometry with a Bose-Einstein Condensate
A Bose-Einstein "double-slit" interferometer has been recently realized
experimentally by (Y. Shin et. al., Phys. Rev. Lett. 92 50405 (2004)). We
analyze the interferometric steps by solving numerically the time-dependent
Gross-Pitaevski equation in three-dimensional space. We focus on the
adiabaticity time scales of the problem and on the creation of spurious
collective excitations as a possible source of the strong dephasing observed
experimentally. The role of quantum fluctuations is discussed.Comment: 4 pages, 3 figure
Role of the relative phase in the merging of two independent Bose-Einstein condensates
We study the merging of two independent Bose-Einstein condensates with
arbitrary initial phase difference, in the framework of a one-dimensional
time-dependent Gross-Pitaevskii model. The role of the initial phase difference
in the process is discussed, and various types of phase-sensitive excitations
are identified.Comment: 19 Pages, 7 figure
On the Creation of the Universe out of Nothing
We explain how the Universe was created with no expenditure of energy or
initial mass.Comment: To be presented at IWARA 2009 (4th International Workshop on
Astronomy and Relativistic Astrophysics), to be held in Brazil, October 200
Dynamical Stability and Quantum Chaos of Ions in a Linear Trap
The realization of a paradigm chaotic system, namely the harmonically driven
oscillator, in the quantum domain using cold trapped ions driven by lasers is
theoretically investigated. The simplest characteristics of regular and chaotic
dynamics are calculated. The possibilities of experimental realization are
discussed.Comment: 24 pages, 17 figures, submitted to Phys. Rev
Transition from isolated to overlapping resonances in the open system of interacting fermions
We study the statistical properties of resonance widths and spacings in an
open system of interacting fermions at the transition between isolated and
overlapping resonances, where a radical change in the width distribution
occurs. Our main interest is to reveal how this transition is influenced by the
onset of chaos in the internal dynamics as the strength of random two-body
interaction between the particles increases. We have found that in the region
of overlapped resonances, the fluctuations of the widths (rather than their
mean values) are strongly affected by the onset of an internal chaos. The
results may be applied to the analysis of neutron cross sections, as well as in
the physics of mesoscopic devices with strongly interacting electrons.Comment: 4 pages, 5 figures, corrected version, figures are replace
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