Showing papers in "Physics Letters A in 1993"

TL;DR: In this article, a complete constructive classification of all discrete ensembles of pure quantum states having a given density matrix is given for all positive operator valued measures with finitely many components, and it is shown that any chosen ensemble consistent with a fixed density matrix can be created at space-like separation using an entangled state depending only on ϱ.

TL;DR: In this article, it is shown that recourse to Tsallis' generalized entropy makes it possible to find sensible distribution functions for stellar polytropes, while that of Boltzmann yields unphysical distributions.

TL;DR: In this paper, a higher-order derivative of supersymmetric quantum mechanics is proposed, which is formally based on the standard superalgebra but supercharges involve differential operators of order n. The Witten index does not characterize spontaneous SUSY breaking in such models.

TL;DR: Pyragas as discussed by the authors proposed a method for chaos control by a small time-continuous perturbation, which is realized experimentally by a specially designed analogue circuit using a simple delay line.

TL;DR: In this article, a new Fabry-Perot-based interferometric gravitational wave detector is proposed, which greatly reduces the amount of power that must be transmitted through optical substrates to obtain a given light power in its arms.

TL;DR: In this paper, the information theory form of the quantum statistical operator that reproduces all available (generalized) expectation values and extremalizes the entropy functional proposed by Tsallis was derived.

TL;DR: In this paper, the exact upper and lower bounds on the information entropies of three spin-1 2 operators S X, S Y, S Z are derived, for a set of more than two observables.

TL;DR: In this paper, a method for stabilizing aperiodic orbits of a strange attractor is proposed, which enables the transformation of an unpredictable chaos into a predictable one by synchronizing the current behavior of a chaotic system with its past behavior.

TL;DR: In this article, it was shown that it is possible to measure the Schrodinger wave of a single quantum system and that the quantum state has physical meaning only for an ensemble of identical systems.

TL;DR: In this paper, the spectrum of fractal dimensions of non-interacting classical and quantum gases in non-equilibrium, whose states are described by the set of occupation numbers { n 1, n 2, … n K }, has been obtained.

TL;DR: In this paper, a modified FitzHugh-Nagumo model for excitable tissue was proposed, where a spiral wave is found to break up into an irregular spatial pattern when the relative refractory period is short and the effect is numerically stable for a five-fold decrease in the space integration step.

TL;DR: Explicit and exact travelling wave solutions are presented for a seventh odder generalized KdV equation, which also provides evidence for a qualitative analysis by Pomeau et al. as mentioned in this paper.

TL;DR: In this article, the dependence of Schrodinger equation eigenvalue problems on the coupling-constant parameters in the potential was considered and it was shown that unless great care is taken, analytic continuation in these parameters can lead to surprising and paradoxical conclusions.

TL;DR: In this article, a method for controlling deterministic chaos by the stabilization of one of the underlying unstable periodic orbits is presented, which works by applying a series of regular proportional feedbacks in the variable.

TL;DR: In contrast to earlier expectations, it is estimated that generation of runaway electrons from close collisions of existing runaways with cold plasma electrons can be significant even for small electric fields, whenever runaways can gain energies of about 20 MeV or more as discussed by the authors.

TL;DR: In the context of nonminimally coupled theories of gravity, the existence of Noether symmetries in pointlike Friedman- Robertson-Walker (FRW) Lagrangians allows one to exactly integrate the dynamics.

TL;DR: In this paper, the authors introduce a simple paradigm to explore how complex, biological systems flexibly recruit and annihilate degrees of freedom according to parametric task requirements, and suggest a theoretical model in which the main qualitative changes observed experimentally are a consequence of two consecutive Hopf bifurcations.

TL;DR: In this article, the Schrodinger equation for interacting systems is used to describe the continuous process of decoherence occurring locally on a very short time scale, while the observer's "increase of information" is appropriately represented by the resulting dynamical decoupling of the corresponding components of the global wave function.

TL;DR: In this article, the mean field solution of the general Blume-Capel model with integer and semi-integer spins was studied and a multiphase point in which the different phases spread out when the temperature is increased was found.

TL;DR: In this article, the contribution of the gravitomagnetic field to the proper time of a standard clock in orbit about a rotating astronomical body is discussed, and the influence of gravitation on the interference of electromagnetic radiation is investigated.

TL;DR: In this paper, the Uhlmann parallel transport for two-dimensional density matrices (spin 1 2 ) explicitly and derive a general formula for the n -dimensional case were derived.

TL;DR: In this article, the gravitational analogue of Larmor's theorem is formulated; the result is then used to study the graviational coupling of the helicity of electromagnetic radiation with the angular momentum of a rotating mass.

TL;DR: In this article, an algebraic treatment of shape-invariant potentials in supersymmetric quantum mechanics is discussed, and it is shown that the introduced coherent state has the property of resolution of unity.

TL;DR: In this article, a general quadratic Poisson bracket on the associative algebra equipped with non-degenerate scalar product is introduced, and the interpretation of the Toda and relativistic Toda lattices as the restrictions of one and the same bi-Hamiltonian system to two different low-dimensional manifolds, which are Poisson submanifolds with respect to two brackets simultaneously.

TL;DR: Its ability to distinguish (noised) multiperiodic and random time series from time series generated by chaotic dynamical systems is demonstrated.

TL;DR: In this article, the spatial pattern in a voter system or an ecosystem is studied by computer simulations, and the authors find a kind of paradox: an initial damage and suppression of one candidate may later lead to an enhancement of the same candidate.

TL;DR: In this article, a noninteracting q-boson system was considered and the mean occupation numbers for the energy levels were derived for the total energy, specific heat, the entropy and the equation of state.

TL;DR: In this article, the second post-Newtonian motion of binary systems consisting of two nonrotating compact objects (e.g. neutron stars) is explicitly given in the form of a generalized quasi-Keplerian parametrization.

TL;DR: In this paper, it was shown that the degenerate single particle ground state has a spin S = 1 2 N e, which is the same spin as the ground state in the general Hubbard model.

TL;DR: In this article, the authors discuss the limit of the Brans-Dicke theory of gravity when ω goes to infinity and show by working out some examples that in this limit it is not always true that this theory reduces to general relativity.