618 research outputs found
Boston Hospitality Review: Fall 2015
U.S. Lodging Industry Update â Q2 2015 by Daniel Lesser and Jonathan Jaeger of LW Hospitality AdvisorsÂź -- Hotel Crowdfunding Grows Up by Joshua Bowman -- Digital Marketing Budgets for Independent Hotels: Continuously Shifting to Remain Competitive in the Online World by Leora Halpern Lanz and Megan Carmichael -- From Patrons to Chefs, a History of Women in Restaurants by Jan Whitaker -- The Bleacher Bar at Fenway Park: Transforming a Former Indoor Batting Cage Into a Unique Eatery and Bar by Graham Ruggie -- Outrageous by Michael Oshin
Violation of Bell Inequalities as a Violation of Fair Sampling in Threshold Detectors
Photomultiplier tubes and avalanche photodiodes, which are commonly used in
quantum optic experiments, are sometimes referred to as threshold detectors
because, in photon counting mode, they cannot discriminate the number of
photoelectrons initially extracted from the absorber in the detector. We argue
that they can be called threshold detectors on more account than that. We point
out that their their functioning principle relies on two thresholds that are
usually thought unimportant individually in the context of EPR-Bell discussion.
We show how the combined effect of these threshold can lead to a significant
sampling selection bias in the detection of pairs of pulses, resulting in an
apparent violation of Bell inequalities.Comment: 11 pages, 8 figures, FPP5 conference, Vaxjo (Sweden) August 200
On Bell's theorem, quantum communication, and entanglement detection
(A) Bell's theorem rests on a conjunction of three assumptions: realism,
locality and ``free will''. A discussion of these assumptions will be
presented.
It will be also shown that, if one adds to the assumptions the principle or
rotational symmetry of physical laws, a stronger version of the theorem
emerges. (B) A link between Bell's theorem and communication complexity
problems will be presented. This also includes experimental realizations, which
surprisingly do not involve entanglement. (C) A new sufficient and necessary
criterion for entanglement of general (mixed) states is be presented. It is
derived using the same geometric starting point as the inclusion of the
symmetry in (A). The set of entanglement identifiers (EI's) emerging via this
method contains entanglement witnesses (EW's), but they form only a subset of
all EI's. Thus the method is more powerful than the one based on EW's.Comment: 10 pages, for proceedings of Foundations of Probability and Physics-5
at Vaxjo University, Swedish Southeast Academy August 24-27, 200
SIC-POVMs and MUBs: Geometrical Relationships in Prime Dimension
The paper concerns Weyl-Heisenberg covariant SIC-POVMs (symmetric
informationally complete positive operator valued measures) and full sets of
MUBs (mutually unbiased bases) in prime dimension. When represented as vectors
in generalized Bloch space a SIC-POVM forms a d^2-1 dimensional regular simplex
(d being the Hilbert space dimension). By contrast, the generalized Bloch
vectors representing a full set of MUBs form d+1 mutually orthogonal d-1
dimensional regular simplices. In this paper we show that, in the
Weyl-Heisenberg case, there are some simple geometrical relationships between
the single SIC-POVM simplex and the d+1 MUB simplices. We go on to give
geometrical interpretations of the minimum uncertainty states introduced by
Wootters and Sussman, and by Appleby, Dang and Fuchs, and of the fiduciality
condition given by Appleby, Dang and Fuchs.Comment: Contribution to the Conference "Foundations of Probability and
Physics-5", Vaxjo, 200
Is Bell's theorem relevant to quantum mechanics? On locality and non-commuting observables
Bell's theorem is a statement by which averages obtained from specific types
of statistical distributions must conform to a family of inequalities. These
models, in accordance with the EPR argument, provide for the simultaneous
existence of quantum mechanically incompatible quantities. We first recall
several contradictions arising between the assumption of a joint distribution
for incompatible observables and the probability structure of
quantum-mechanics, and conclude that Bell's theorem is not expected to be
relevant to quantum phenomena described by non-commuting observables,
irrespective of the issue of locality. Then, we try to disentangle the locality
issue from the existence of joint distributions by introducing two models
accounting for the EPR correlations but denying the existence of joint
distributions. We will see that these models do not need to resort explicitly
to non-locality: the first model relies on conservation laws for ensembles, and
the second model on an equivalence class by which different configurations lead
to the same physical predictions.Comment: Extended with new materia
Bohm's quantum potential and quantum force in superconductor
The Bohm's quantum potential, introduced in 1952, and the quantum force in
superconductor, introduced in 2001, allow to describe non-local force-free
momentum transfer observed in the Ahronov-Bohm effects. Comparison of the
Ahronov-Bohm effects in the two-slit interference experiment and in
superconductor ring reveals fundamental difference between the Schrodinger wave
function and the wave function describing macroscopic quantum phenomena. The
Ginzburg-Landau wave function describing the superconductivity phenomenon can
not collapse and an additional postulate, which was implied first by L.D.
Landau, must be used for the description of macroscopic quantum phenomena. It
is note that quantum principles and postulates should not be universal till the
quantum formalism is only phenomenological theory but no description of an
unique reality. A simple Gedankenexperiment is considered which challenges the
universality of the Heisenberg uncertainty relation and the Bohr's
complementarity principle.Comment: 9 pages, 1 figure, the Invited talk was presented at the conference
"Foundations of Probability and Physics-5" Vaxjo University, Sweden, August
24-27, 200
Priors in quantum Bayesian inference
In quantum Bayesian inference problems, any conclusions drawn from a finite
number of measurements depend not only on the outcomes of the measurements but
also on a prior. Here we show that, in general, the prior remains important
even in the limit of an infinite number of measurements. We illustrate this
point with several examples where two priors lead to very different conclusions
given the same measurement data.Comment: 7 pages; published in AIP Conference Proceedings 1101: Foundations of
Probability and Physics 5, edited by L. Accardi et al, p. 255 (2009
Generation and Properties of Snarks
For many of the unsolved problems concerning cycles and matchings in graphs
it is known that it is sufficient to prove them for \emph{snarks}, the class of
nontrivial 3-regular graphs which cannot be 3-edge coloured. In the first part
of this paper we present a new algorithm for generating all non-isomorphic
snarks of a given order. Our implementation of the new algorithm is 14 times
faster than previous programs for generating snarks, and 29 times faster for
generating weak snarks. Using this program we have generated all non-isomorphic
snarks on vertices. Previously lists up to vertices have been
published. In the second part of the paper we analyze the sets of generated
snarks with respect to a number of properties and conjectures. We find that
some of the strongest versions of the cycle double cover conjecture hold for
all snarks of these orders, as does Jaeger's Petersen colouring conjecture,
which in turn implies that Fulkerson's conjecture has no small counterexamples.
In contrast to these positive results we also find counterexamples to eight
previously published conjectures concerning cycle coverings and the general
cycle structure of cubic graphs.Comment: Submitted for publication V2: various corrections V3: Figures updated
and typos corrected. This version differs from the published one in that the
Arxiv-version has data about the automorphisms of snarks; Journal of
Combinatorial Theory. Series B. 201
A Flexible Tool to Correct Superimposed Mass Isotopologue Distributions in GC-APCI-MS Flux Experiments
The investigation of metabolic fluxes and metabolite distributions within cells by means of tracer molecules is a valuable tool to unravel the complexity of biological systems. Technological advances in mass spectrometry (MS) technology such as atmospheric pressure chemical ionization (APCI) coupled with high resolution (HR), not only allows for highly sensitive analyses but also broadens the usefulness of tracer-based experiments, as interesting signals can be annotated de novo when not yet present in a compound library. However, several effects in the APCI ion source, i.e., fragmentation and rearrangement, lead to superimposed mass isotopologue distributions (MID) within the mass spectra, which need to be corrected during data evaluation as they will impair enrichment calculation otherwise. Here, we present and evaluate a novel software tool to automatically perform such corrections. We discuss the different effects, explain the implemented algorithm, and show its application on several experimental datasets. This adjustable tool is available as an R package from CRAN.SALSA (School of Analytical Sciences Adlershof, Albert-Einstein-StraĂe 5, 12489 Berlin, Germany)Peer Reviewe
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