334 research outputs found
No-go theorem for the composition of quantum systems
Building on the Pusey-Barrett-Rudolph theorem, we derive a no-go theorem for
a vast class of deterministic hidden-variables theories, including those
consistent on their targeted domain. The strength of this result throws doubt
on seemingly natural assumptions (like the "preparation independence" of the
Pusey-Barrett-Rudolph theorem) about how "real states" of subsystems compose
for joint systems in nonentangled states. This points to constraints in
modeling tensor-product states, similar to constraints demonstrated for more
complex states by the Bell and Bell-Kochen-Specker theorems.Comment: 4 pages. v2: new title, significant revisions. v3: condensed, matches
final published versio
A local hidden variable theory for the GHZ experiment
A recent analysis by de Barros and Suppes of experimentally realizable GHZ
correlations supports the conclusion that these correlations cannot be
explained by introducing local hidden variables. We show, nevertheless, that
their analysis does not exclude local hidden variable models in which the
inefficiency in the experiment is an effect not only of random errors in the
detector equipment, but is also the manifestation of a pre-set, hidden property
of the particles ("prism models"). Indeed, we present an explicit prism model
for the GHZ scenario; that is, a local hidden variable model entirely
compatible with recent GHZ experiments.Comment: 17 pages, LaTeX, 7 eps figures, computer demo:
http://hps.elte.hu/~leszabo/GHZ.html, an improper figure is replace
The number of primary events per variable affects estimation of the subdistribution hazard competing risks model
AbstractObjectivesTo examine the effect of the number of events per variable (EPV) on the accuracy of estimated regression coefficients, standard errors, empirical coverage rates of estimated confidence intervals, and empirical estimates of statistical power when using the Fine–Gray subdistribution hazard regression model to assess the effect of covariates on the incidence of events that occur over time in the presence of competing risks.Study Design and SettingMonte Carlo simulations were used. We considered two different definitions of the number of EPV. One included events of any type that occurred (both primary events and competing events), whereas the other included only the number of primary events that occurred.ResultsThe definition of EPV that included only the number of primary events was preferable to the alternative definition, as the number of competing events had minimal impact on estimation. In general, 40–50 EPV were necessary to ensure accurate estimation of regression coefficients and associated quantities. However, if all of the covariates are continuous or are binary with moderate prevalence, then 10 EPV are sufficient to ensure accurate estimation.ConclusionAnalysts must base the number of EPV on the number of primary events that occurred
The Ithaca Interpretation of Quantum Mechanics
I list several strong requirements for what I would consider a sensible
interpretation of quantum mechanics and I discuss two simple theorems. One, as
far as I know, is new; the other was only noted a few years ago. Both have
important implications for such a sensible interpretation. My talk will not
clear everything up; indeed, you may conclude that it has not cleared anything
up. But I hope it will provide a different perspective from which to view some
old and vexing puzzles (or, if you believe nothing needs to be cleared up, some
ancient verities.)Comment: 21 pages, plain TEX. Notes for a lecture given at the Golden Jubilee
Workshop on Foundations of Quantum Theory, Tata Institute, Bombay, September
9-12, 199
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