42,537 research outputs found
Properties of a magnetic superconductor with weak magnetization - application to
Using a Ginsburg-Landau free energy functional, we study the phase
diagram of a weak magnetic superconductor, where the magnetization from the
magnetic component is marginal in supporting a spontaneous vortex phase in
absence of external magnetic field. In particular, the competition between the
spiral state and spontaneous vortex phase is analysed. Our theory is applied to
understand the magnetic properties of .Comment: 13 pages, 4 postscript figure
Dynamical stability of entanglement between spin ensembles
We study the dynamical stability of the entanglement between the two spin
ensembles in the presence of an environment. For a comparative study, we
consider the two cases: a single spin ensemble, and two ensembles linearly
coupled to a bath, respectively. In both circumstances, we assume the validity
of the Markovian approximation for the bath. We examine the robustness of the
state by means of the growth of the linear entropy which gives a measure of the
purity of the system. We find out macroscopic entangled states of two spin
ensembles can stably exist in a common bath. This result may be very useful to
generate and detect macroscopic entanglement in a common noisy environment and
even a stable macroscopic memory.Comment: 4 pages, 1 figur
Steady-state entanglement in a double-well Bose-Einstein condensate through coupling to a superconducting resonator
We consider a two-component Bose-Einstein condensate in a double-well
potential, where the atoms are magnetically coupled to a single-mode of the
microwave field inside a superconducting resonator. We find that the system has
the different dark-state subspaces in the strong- and weak-tunneling regimes,
respectively. In the limit of weak tunnel coupling, steady-state entanglement
between the two spatially separated condensates can be generated by evolving to
a mixture of dark states via the dissipation of the photon field. We show that
the entanglement can be faithfully indicated by an entanglement witness.
Long-lived entangled states are useful for quantum information processing with
atom-chip devices.Comment: 9 pages, 7 figures, minor revisio
Regular expressions as violin bowing patterns
String players spend a significant amount of practice time creating and learning bowings. These may be indicated in the music using up-bow and down-bow symbols, but those traditional notations do not capture the complex bowing patterns that are latent within the music. Regular expressions, a mathematical notation for a simple class of formal languages, can describe precisely the bowing patterns that commonly arise in string music. A software tool based on regular expressions enables performers to search for passages that can be handled with similar bowings, and to edit them consistently. A computer-based music editor incorporating bowing patterns has been implemented, using Lilypond to typeset the music. Our approach has been evaluated by using the editor to study ten movements from six violin sonatas by W. A. Mozart. Our experience shows that the editor is successful at finding passages and inserting bowings; that relatively complex patterns occur a number of times; and that the bowings can be inserted automatically and consistently
Visualization of leading edge vortices on a series of flat plate delta wings
A summary of flow visualization data obtained as part of NASA Grant NAG2-258 is presented. During the course of this study, many still and high speed motion pictures were taken of the leading edge vortices on a series of flat plate delta wings at varying angles of attack. The purpose is to present a systematic collection of photographs showing the state of vortices as a function of the angle of attack for the four models tested
Precision measurement with an optical Josephson junction
We study a new type of Josephson device, the so-called "optical Josephson
junction" as proposed in Phys. Rev. Lett. {\bf 95}, 170402 (2005). Two
condensates are optically coupled through a waveguide by a pair of Bragg beams.
This optical Josephson junction is analogous to the usual Josephson junction of
two condensates weakly coupled via tunneling. We discuss the use of this
optical Josephson junction, for making precision measurements.Comment: 6 pages, 1 figur
Idealized Slab Plasma approach for the study of Warm Dense Matter
Recently, warm dense matter (WDM) has emerged as an interdisciplinary field
that draws increasing interest in plasma physics, condensed matter physics,
high pressure science, astrophysics, inertial confinement fusion, as well as
materials science under extreme conditions. To allow the study of well-defined
WDM states, we have introduced the concept of idealized-slab plasmas that can
be realized in the laboratory via (i) the isochoric heating of a solid and (ii)
the propagation of a shock wave in a solid. The application of this concept
provides new means for probing the dynamic conductivity, equation of state,
ionization and opacity. These approaches are presented here using results
derived from first-principles (density-functional type) theory, Thomas-Fermi
type theory, and numerical simulations.Comment: 37 pages, 21 figures, available, pdf file only. To appear in: Laser
and Particle beams. To appear more or less in this form in Laser and Particle
beam
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