1,570 research outputs found
Modeling the Singlet State with Local Variables
A local-variable model yielding the statistics from the singlet state is
presented for the case of inefficient detectors and/or lowered visibility. It
has independent errors and the highest efficiency at perfect visibility is
77.80%, while the highest visibility at perfect detector-efficiency is 63.66%.
Thus, the model cannot be refuted by measurements made to date.Comment: 15 pages, 13 figure
Quantum optics with bosons and fermions
Atom optics, a field which takes much inspiration from traditional optics,
has advanced to the point that some of the fundamental experiments of quantum
optics, involving photon correlations, have found atomic analogs. We discuss
some recent experiments on atom bunching and anti-bunching as well as some
prospects for extending them to the field of many body physics.Comment: English version of "Optique atomique quantique : apr\`es les bosons,
les fermions
Operational Characterization of Simultaneous Measurements in Quantum Mechanics
Quantum mechanics predicts the joint probability distribution of the outcomes
of simultaneous measurements of commuting observables, but, in the state of the
art, has lacked the operational definition of simultaneous measurements. The
question is answered as to when the consecutive applications of measuring
apparatuses give a simultaneous measurement of their observables. For this
purpose, all the possible state reductions caused by measurements of an
observable is also characterized by their operations.Comment: 9 pages, REVTe
Decoherence at absolute zero
We present an analytical study of the loss of quantum coherence at absolute
zero. Our model consists of a harmonic oscillator coupled to an environment of
harmonic oscillators at absolute zero. We find that for an Ohmic bath, the
offdiagonal elements of the density matrix in the position representation decay
as a power law in time at late times. This slow loss of coherence in the
quantum domain is qualitatively different from the exponential decay observed
in studies of high temperature environments.Comment: Published in Physics Letters
Testing temporal Bell inequalities through repeated measurements in rf-SQUIDs
Temporal Bell-like inequalities are derived taking into account the influence
of the measurement apparatus on the observed magnetic flux in a rf-SQUID.
Quantum measurement theory is shown to predict violations of these inequalities
only when the flux states corresponding to opposite current senses are not
distinguishable. Thus rf-SQUIDs cannot help to discriminate realism and quantum
mechanics at the macroscopic level.Comment: 12 pages, 4 Postscript figures in an uuencoded file figures.uu, uses
revtex.st
Bell's inequalities I: An explanation for their experimental violation
Derivations of two Bell's inequalities are given in a form appropriate to the
interpretation of experimental data for explicit determination of all the
correlations. They are arithmetic identities independent of statistical
reasoning and thus cannot be violated by data that meets the conditions for
their validity. Two experimentally performable procedures are described to meet
these conditions. Once such data are acquired, it follows that the measured
correlations cannot all equal a negative cosine of angular differences. The
relation between this finding and the predictions of quantum mechanics is
discussed in a companion paper.Comment: 15 pages, 2 figure
Spontaneous parity breaking of graphene in the quantum Hall regime
We propose that the inversion symmetry of the graphene honeycomb lattice is
spontaneously broken via a magnetic field dependent Peierls distortion. This
leads to valley splitting of the Landau level but not of the other Landau
levels. Compared to quantum Hall valley ferromagnetism recently discussed in
the literature, lattice distortion provides an alternative explanation to all
the currently observed quantum Hall plateaus in graphene.Comment: 4 pages, to appear in Phys. Rev. Let
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