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Quantum States (quantum + states)

Distribution by Scientific Domains

Physics and Astronomy	70%

Selected Abstracts

A probabilistic approach to quantum mechanics based on ,tomograms'

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 7 2006
M. Caponigro
It is usually believed that a picture of Quantum Mechanics in terms of true probabilities cannot be given due to the uncertainty relations. Here we discuss a tomographic approach to quantum states that leads to a probability representation of quantum states. This can be regarded as a classical-like formulation of quantum mechanics which avoids the counterintuitive concepts of wave function and density operator. The relevant concepts of quantum mechanics are then reconsidered and the epistemological implications of such approach discussed. [source]

Criteria for the entanglement of composite systems with identical particles

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 11-12 2004
G.C. Ghirardi
We identify a general criterion for detecting entanglement of pure bipartite quantum states describing a system of two identical particles. Such a criterion is based both on the consideration of the Slater-Schmidt number of the fermionic and bosonic analog of the Schmidt decomposition and on the evaluation of the von Neumann entropy of the one-particle reduced statistical operators. [source]

Quantum interferometry with intense optical pulses

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 4-5 2003
G. Leuchs
For intense optical pulses the optical Kerr interaction in matter such as an optical fiber is large enough to generate quantum states of light with significant non-classical properties. On this basis pairs of entangled light pulses have been generated. This entanglement can be used for novel schemes in high precision interferometry and for quantum communication protocols such as quantum dense coding. [source]

From unambiguous quantum state discrimination to quantum state filtering

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 2-3 2003
J.A. Bergou
Unambiguous discrimination among nonorthogonal but linearly independent quantum states is possible with a certain probability of success. Here, we consider a new variant of that problem. Instead of discriminating among all of the N different states, we now ask for less. We want to unambiguously assign the state to one of two complementary subsets of the set of N given non-orthogonal quantum states, each occurring with given a priori probabilities. We refer to the special case when one subset contains only one state and the other contains the remaining N -1 states as unambiguous quantum state filtering. We present an optimal analytical solution for the special case of N=3, and discuss the optimal strategy to unambiguously distinguish |,1, from the set {|,2,,|,3,}. For unambiguous filtering the subsets need not be linearly independent. We briefly discuss how to construct generalized interferometers (multiports) which provide a fully linear optical implementation of the optimal strategy. [source]

Quantum measurement and information

FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 2-3 2003
Z. Hradil
The operationally defined invariant information introduced by Brukner and Zeilinger is related to the problem of estimation of quantum states. It quantifies how the estimated states differ in average from the true states in the sense of Hilbert-Schmidt norm. This information evaluates the quality of the measurement and data treatment adopted. Its ultimate limitation is given by the trace of inverse of Fisher information matrix. [source]

Application of the asymptotic iteration method to the exponential cosine screened Coulomb potential

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2007
O. Bayrak
Abstract We present the iterative solutions of the radial Schrödinger equation for the exponential cosine screened Coulomb (ECSC) potential for any n and l quantum states by applying the asymptotic iteration method (AIM). We show that it is possible to obtain the solution as accurate as the other methods without any perturbation. Furthermore, there are no tedious mathematical difficulties and restrictions on finding the energy eigenvalues for any n and l quantum numbers. Our results are in excellent agreement with the ones published in the literature. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [source]

Wigner function of the rotating Morse oscillator

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 1 2005
Jerzy Stanek
Abstract We present an analytical expression of the Wigner distribution function (WDF) for the bound eigenstates of the rotating Morse oscillator (RMO). The effect of rotational excitation on the WDF on the quantum phase space has been demonstrated. This effect has been visualized by a series of contour diagrams for given rovibrational quantum states. Rotations of the molecule have been proved to qualitatively and quantitatively change the Wigner function. As a result, the most probable distance between atoms in a rotating molecule changes, and depends on the parity of the vibrational quantum number. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005 [source]

Discrete and continuum quantum states for the Kratzer oscillator

INTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 3 2002
Adelio R. MatamalaArticle first published online: 2 JUL 200
Abstract Kratzer oscillator is a realistic zero-order model for describing the anharmonic ro-vibrational motion in diatomic molecules. Kratzer oscillator has an energy spectrum containing both discrete and continuum parts. Wavefunctions belonging to the continuum would be useful in the study of transitions to the continuum in molecular dissociation processes. In this article, bound and scattering wavefunctions of the Kratzer oscillator are reviewed and the bound,bound and the bound,free matrix elements are obtained. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2002 [source]

Linear extension of the Robinson,Schensted algorithm

PHYSICA STATUS SOLIDI (B) BASIC SOLID STATE PHYSICS, Issue 2 2005
P. Jakubczyk
Abstract The Robinson,Schensted (RS) algorithm demonstrates a bijection between the set of magnetic configurations f and the set of pairs of tableaux: a semistandard Weyl tableau P(f) accompanied by a standard Young tableau Q(f). We show that it is not only a bijection between sets, but it can be extended to a linear unitary transformation within the space of all quantum states of the magnet. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

FRW minisuperspace with local N=4 supersymmetry and self-interacting scalar field

ANNALEN DER PHYSIK, Issue 3 2003
P. Vargas Moniz
Abstract A supersymmetric FRW model with a scalar supermultiplet and generic superpotential is analysed from a quantum cosmological perspective. The corresponding Lorentz and supersymmetry constraints allow to establish a system of first order partial differential equations from which solutions can be obtained. We show that this is possible when the superpotential is expanded in powers of a parameter ,,1. At order ,0 we find the general class of solutions, which include in particular quantum states reported in the current literature. New solutions are partially obtained at order ,1, where the dependence on the superpotential is manifest. These classes of solutions can be employed to find states for higher orders in ,. Our analysis further points to the following: (i) supersymmetric wave functions can only be found when the superpotential has either an exponential behaviour, an effective cosmological constant form or is zero; (ii) If the superpotential behaves differently during other periods, the wave function is trivial ( = 0, i.e., no supersymmetric states). We conclude this paper discussing how our FRW minisuperspace (with N = 4 supersymmetry and invariance under time-reparametrization) can be relevant concerning the issue of supersymmetry breaking. [source]