23,890 research outputs found
Entanglement of internal and external angular momenta of a single atom
We consider the exchange of spin and orbital angular momenta between a
circularly polarized Laguerre-Gaussian beam of light and a single atom trapped
in a two-dimensional harmonic potential. The radiation field is treated
classically but the atomic center-of-mass motion is quantized. The spin and
orbital angular momenta of the field are individually conserved upon
absorption, and this results in the entanglement of the internal and external
degrees of freedom of the atom. We suggest applications of this entanglement in
quantum information processing.Comment: 4 pages, 2 figure
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Boloñský proces se odráží i v budoucnosti chemicky orientovaných stredních škol
Impact of birth weight and gender on early postnatal hypothalamic energy balance regulatory gene expression in the young lamb
Peer reviewedPreprin
and Perelomov number coherent states: algebraic approach for general systems
We study some properties of the Perelomov number coherent states.
The Schr\"odinger's uncertainty relationship is evaluated for a position and
momentum-like operators (constructed from the Lie algebra generators) in these
number coherent states. It is shown that this relationship is minimized for the
standard coherent states. We obtain the time evolution of the number coherent
states by supposing that the Hamiltonian is proportional to the third generator
of the Lie algebra. Analogous results for the Perelomov
number coherent states are found. As examples, we compute the Perelomov
coherent states for the pseudoharmonic oscillator and the two-dimensional
isotropic harmonic oscillator
Design and performance of a multicentre, randomized controlled trial of teleconsulting.
We have designed and performed a multicentre, randomized controlled trial of teleconsulting. The trial investigated the effectiveness and cost implications in rural and inner-city settings of using videoconferencing as an alternative to general practitioner referral to a hospital specialist. The participating general practitioners referred a total of 3170 patients who satisfied the entry criteria. Of these, 1040 (33%) failed to provide consent or otherwise refused to participate in the trial. Of the patients recruited to the trial, a total of 1902 (91%) completed and returned the baseline questionnaire. Although the trial was successful in recruiting sufficient patients and in obtaining high questionnaire response rates, the findings will require careful interpretation to take account of the limits which the protocol placed on the ability of general practitioners to select patients for referral
Vortex interaction, chaos and quantum probabilities
The motion of a single vortex is able to originate chaos in the quantum
trajectories defined in Bohm's interpretation of quantum mechanics. In this
Letter, we show that this is also the case in the general situation, in which
many interacting vortices exist. This result gives support to recent attempts
in which Born's probability rule is derived in terms of an irreversible time
evolution to equilibrium, rather than being postulated.Comment: 4 pages, 4 figure
Two-Band-Type Superconducting Instability in MgB2
Using the tight-binding method for the -bands in MgB, the Hubbard
on-site Coulomb interaction on two inequivalent boron -orbitals is
transformed into expressions in terms of -band operators. For scattering
processes relevant to the problemin which a wave vector {\bf q} is parallel to
, it is found to take a relatively simple form consisting of
intra-band Coulomb scattering, interband pair scattering etc. with large
constant coupling constants. This allows to get a simple expression for the
amplitude of interband pair scattering between two -bands, which diverges
if the interband polarization function in it becomes large enough.The latter
was approximately evaluated and found to be largely enhanced in the band
structure in MgB. These results lead to a divergent interband pair
scattering, meaning two-band-type superconducting instability with enhanced
. Adding a subsidiary BCS attractive interaction in each band into
consideration, a semi-quantitative gap equation is given, and and isotope
exponent are derived. The present instability is asserted to be the
origin of high in MgB.Comment: 4 pages, to be published in J. Phys. Soc. Jpn. vol. 70, No.
Superconducting charge qubits from a microscopic many-body perspective
The quantised Josephson junction equation that underpins the behaviour of
charge qubits and other tunnel devices is usually derived through cannonical
quantisation of the classical macroscopic Josephson relations. However, this
approach may neglect effects due to the fact that the charge qubit consists of
a superconducting island of finite size connected to a large superconductor.
We show that the well known quantised Josephson equation can be derived
directly and simply from a microscopic many-body Hamiltonian. By choosing the
appropriate strong coupling limit we produce a highly simplified Hamiltonian
that nevertheless allows us to go beyond the mean field limit and predict
further finite-size terms in addition to the basic equation.Comment: Accepted for J Phys Condensed Matte
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