arXiv.org e-Print Archive

    The Schwarz-Hora effect: present-day situation

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    The electron-diffraction pattern at a nonfluorescent target was observed by Schwarz under attempts to modulate an electron beam by laser light. The pattern was of the same color as the laser light. The analysis of the literature shows there are the unresolved up to now significant contradictions between the theory and the Schwarz experiments. To resolve these contradictions, the interpretation of the Schwarz-Hora effect is considered, which is a development of the idea formulated by Schwarz and Hora. It is supposed that the interaction of electrons with the laser field inside a thin dielectric film is accompanied not only by the processes of absorption and stimulated emission of photons but also by formation of some metastable electron states in which the captured photons can be transferred with a following emission at the target.Comment: 5 pages, RevTex, 2 PS figure

    Quantum Probability from Decision Theory?

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    Deutsch has recently (in quant-ph/9906015) offered a justification, based only on the non-probabilistic axioms of quantum theory and of classical decision theory, for the use of the standard quantum probability rules. In this note, this justification is examined.Comment: LaTeX, 5 pages, no figure

    Threshold and linewidth of a mirrorless parametric oscillator

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    We analyze the above-threshold behavior of a mirrorless parametric oscillator based on resonantly enhanced four wave mixing in a coherently driven dense atomic vapor. It is shown that, in the ideal limit, an arbitrary small flux of pump photons is sufficient to reach the oscillator threshold. We demonstrate that due to the large group-velocity delays associated with coherent media, an extremely narrow oscillator linewidth is possible, making a narrow-band source of non-classical radiation feasible.Comment: revised version to appear in Phys.Rev.Lett., contains discussion on threshold conditions and operation on few-photon leve

    Time-convolutionless reduced-density-operator theory of a noisy quantum channel: a two-bit quantum gate for quantum information processing

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    An exact reduced-density-operator for the output quantum states in time-convolutionless form was derived by solving the quantum Liouville equation which governs the dynamics of a noisy quantum channel by using a projection operator method and both advanced and retarded propagators in time. The formalism developed in this work is general enough to model a noisy quantum channel provided specific forms of the Hamiltonians for the system, reservoir, and the mutual interaction between the system and the reservoir are given. Then, we apply the formulation to model a two-bit quantum gate composed of coupled spin systems in which the Heisenberg coupling is controlled by the tunneling barrier between neighboring quantum dots. Gate Characteristics including the entropy, fidelity, and purity are calculated numerically for both mixed and entangled initial states

    Cold Atoms For Testing Quantum Mechanics and Parity Violation In Gravitation

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    Techniques of Atom trapping and laser cooling have proved to be very important tools in probing many aspects of fundamental physics. In this talk I wish to present ideas on how they may used to settle certain issues in the foundational aspects of quantum mechanics on the one hand and about some quantum gravitational interactions of matter that violate parity and time-reversal, on the other hand.Comment: Revtex, 8 page

    MR spectroscopy with parabolic magnetic field: spin-oscillator coupling effect

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    The spectrum of the spin particle in oscillatory potential subjected to external parabolic magnetic field ${\bf B}=(B_0+Gx+\tilde G x^2){\bf \hat z}$ is obtained. The structure of energy levels of the considered system allows to identify the frequency of the oscillator via the spectrum of spin sublevels coming only from {\it one} oscillatory level. The effect is due to the gradient terms in the form of the field.Comment: RevTeX, 3 page

    Explanation of Quantum Mechanics

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    By assuming that the kinetic energy,potential energy,momentum,and some other physical quantities of a particle exist in the field out of the particle,the Schrodinger equation is an equation describing field of a particle,but not the particle itself.Comment: LaTex,2 page

    Conditionally Exactly Solvable Potentials and Supersymmetric Transformations

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    A general procedure is presented to construct conditionally solvable (CES) potentials using the techniques of supersymmetric quantum mechanics.The method is illustrated with potentials related to the harmonic oscillator problem.Besides recovering known results,new CES potentials are also obtained within the framework of this general approach.The conditions under which this method leads to CES potentials are also discussed.Comment: 10 pages,Reference adde

    Distillability and partial transposition in bipartite systems

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    We study the distillability of a certain class of bipartite density operators which can be obtained via depolarization starting from an arbitrary one. Our results suggest that non-positivity of the partial transpose of a density operator is not a sufficient condition for distillability, when the dimension of both subsystems is higher than two.Comment: 8 pages, 1 figur

    Forced generation of simple and double emulsions in all-aqueous system

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    We report an easy-to-implement method that allows the direct generation of water-in-water (w/w) single emulsions. The method relies on direct perturbation of the pressure that drives the flow of the dispersed phase of the emulsions. The resultant inner jet is induced to break up into droplets due to the growth of the perturbation through Rayleigh-Plateau instability [L. Rayleigh, Proc. R. Soc. London 29, 71-97 (1879)]; this leads to the formation of monodisperse droplets. By implementing this method on a modified microfluidic device, we directly generate water-in-water-in-water (w/w/w) double emulsions with good control over the size and the number of encapsulated droplets. Our approach suggests a new route to apply droplet-based microfluidics to completely water-based systems
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