Comment on ``Hidden quantum nonlocality revealed by local filters''

In Section 3 of his paper (N. Gisin, Phys. Lett. A 210 (1996) 151), Gisin argues that a ``careless application of generalized quantum measurements can violate Bell's inequality even for mixtures of product states.'' However, the observed violation of the CHSH inequality is not in fact due to the application of generalized quantum measurements, but rather to a misapplication of the inequality itself -- to conditional expectations in which the conditioning depends upon the measurements under consideration.Comment: 3 pages, submitted to Physics Letters

Time and Ensemble Averages in Bohmian Mechanics

We show that in the framework of one-dimensional Bohmian Quantum Mechanics[1], for a particle subject to a potential undergoing a weak adiabatic change, the time averages of the particle's positions typically differ markedly from the ensemble averages. We Apply this result to the case where the weak perturbing potential is the back-action of a measuring device (i.e. a protective measurement). It is shown that under these conditions, most trajectories never cross the position measured (as already shown for a particular example in [3]).Comment: 6 page

Quantitative estimates of discrete harmonic measures

A theorem of Bourgain states that the harmonic measure for a domain in ℝ d is supported on a set of Hausdorff dimension strictly less thand [2]. We apply Bourgain's method to the discrete case, i.e., to the distribution of the first entrance point of a random walk into a subset of ℤ d ,d≥2. By refining the argument, we prove that for allβ>0 there existsρ(d,β)N(d,β), anyx ∈ ℤ d , and anyA ⊂ {1, ,n} d •{y∈ℤ whereν A,x (y) denotes the probability thaty is the first entrance point of the simple random walk starting atx intoA. Furthermore,ρ must converge tod asβ →

Time of Arrival from Bohmian Flow

We develop a new conception for the quantum mechanical arrival time distribution from the perspective of Bohmian mechanics. A detection probability for detectors sensitive to quite arbitrary spacetime domains is formulated. Basic positivity and monotonicity properties are established. We show that our detection probability improves and generalises earlier proposals by Leavens and McKinnon. The difference between the two notions is illustrated through application to a free wave packet.Comment: 18 pages, 8 figures, to appear in Journ. Phys. A; representation of ref. 5 improved (thanks to Rick Leavens

Feynman's Path Integrals and Bohm's Particle Paths

Both Bohmian mechanics, a version of quantum mechanics with trajectories, and Feynman's path integral formalism have something to do with particle paths in space and time. The question thus arises how the two ideas relate to each other. In short, the answer is, path integrals provide a re-formulation of Schroedinger's equation, which is half of the defining equations of Bohmian mechanics. I try to give a clear and concise description of the various aspects of the situation.Comment: 4 pages LaTeX, no figures; v2 shortened a bi

A Subtlety of the Schr\"{o}dinger Picture Dynamics

We address a mathematical and physical status of exotic (like e.g. fractal) wave packets and their quantum dynamics. To this end, we extend the formal meaning of the Schr\"{o}dinger equation beyond the domain of the Hamiltonian. The dynamical importance of the finite mean energy condition is elucidated.Comment: Minor amendments, typos corrected, to appear in Rep. Math. Phy

Hypersurface Bohm-Dirac models

We define a class of Lorentz invariant Bohmian quantum models for N entangled but noninteracting Dirac particles. Lorentz invariance is achieved for these models through the incorporation of an additional dynamical space-time structure provided by a foliation of space-time. These models can be regarded as the extension of Bohm's model for N Dirac particles, corresponding to the foliation into the equal-time hyperplanes for a distinguished Lorentz frame, to more general foliations. As with Bohm's model, there exists for these models an equivariant measure on the leaves of the foliation. This makes possible a simple statistical analysis of position correlations analogous to the equilibrium analysis for (the nonrelativistic) Bohmian mechanics.Comment: 17 pages, 3 figures, RevTex. Completely revised versio

On the classical limit of Bohmian mechanics for Hagedorn wave packets

We consider the classical limit of quantum mechanics in terms of Bohmian trajectories. For wave packets as defined by Hagedorn we show that the Bohmian trajectories converge to Newtonian trajectories in probability.Comment: some minor changes; published versio

No Two Courses Alike Yet All Basic Education. A plea for an open, nonhomogeneous and diverse basic education landscape modelled on basic education in practice at ISOP

In den letzten Jahren häuft sich das Angebot homogener Kurse für junge MigrantInnen, die in das hiesige Ausbildungssystem integriert werden sollen. Diese Kurse erinnern an Schule und haben – bis auf relevante Inhalte – wenig mit der klassischen, alltagsorientierten Basisbildung für Erwachsene in ihren vielfältigen Formen gemein. Die AutorInnen dieses Beitrages plädieren wider einem zu eng gesetzten Begriff von Basisbildung für Vielfalt in der Basisbildungslandschaft, für soziales Lernen, für offene Lernformate und inhomogene TeilnehmerInnengruppen. Hierfür legen sie die konkrete Basisbildungspraxis von ISOP – Innovative Sozialprojekte GmbH offen, einer Non-Profit Bildungsorganisation in der Steiermark, die auf 20 Jahre praktische Erfahrung zurückgreift. Wie sieht eine alltagsorientierte Basisbildungsarbeit mit und für eine inhomogene TeilnehmerInnengruppe aus? Welchen Herausforderungen stellen sich die TrainerInnen? Den Abschluss bilden mahnende Fragen: Wie lange wird es in Österreich noch Basisbildung mit freiem Zugang, unbestimmter Kursdauer, Alltagsverwertbarkeit, kleiner Gruppengröße, vielfältigen, inhomogenen Gruppen geben? Kann und will sich unsere Gesellschaft dieses Nischenangebot weiterhin leisten? (DIPF/Orig.)Recently there has been a boom in offerings of homogeneous courses for young migrants who should be integrated into the current educational system. These courses are reminiscent of school and – except for relevant content – have little in common with classic basic education for adults in it’s diverse forms that is oriented toward everyday life. Contrary to a too narrow concept of basic education, the authors of this article call for diversity in the basic education landscape, social learning, open forms of learning and nonhomogeneous groups of participants. They present the example of the specific practice of basic education at ISOP – Innovative Sozialprojekte GmbH, a non-profit educational organisation in Styria with 20 years of practical experience. What does basic education oriented toward everyday life with and for a nonhomogeneous group of participants look like? What challenges do the trainers face? The conclusion raises questions as a warning: How long will basic education with open access, indeterminate length of courses, applicability to everyday life, small groups, diverse, nonhomogeneous groups still be available in Austria? Can our society afford this niche offering and does it still want to? (DIPF/Orig.