760 research outputs found
Weak Energy: Form and Function
The equation of motion for a time-independent weak value of a quantum
mechanical observable contains a complex valued energy factor - the weak energy
of evolution. This quantity is defined by the dynamics of the pre-selected and
post-selected states which specify the observable's weak value. It is shown
that this energy: (i) is manifested as dynamical and geometric phases that
govern the evolution of the weak value during the measurement process; (ii)
satisfies the Euler-Lagrange equations when expressed in terms of Pancharatnam
(P) phase and Fubini-Study (FS) metric distance; (iii) provides for a PFS
stationary action principle for quantum state evolution; (iv) time translates
correlation amplitudes; (v) generalizes the temporal persistence of state
normalization; and (vi) obeys a time-energy uncertainty relation. A similar
complex valued quantity - the pointed weak energy of an evolving state - is
also defined and several of its properties in PFS-coordinates are discussed. It
is shown that the imaginary part of the pointed weak energy governs the state's
survival probability and its real part is - to within a sign - the
Mukunda-Simon geometric phase for arbitrary evolutions or the Aharonov-Anandan
(AA) phase for cyclic evolutions. Pointed weak energy gauge transformations and
the PFS 1-form are discussed and the relationship between the PFS 1-form and
the AA connection 1-form is established.Comment: To appear in "Quantum Theory: A Two-Time Success Story"; Yakir
Aharonov Festschrif
Deformations at Earth's dayside magnetopause during quasi-radial IMF conditions: Global kinetic simulations and soft X-ray imaging
The Solar wind Magnetosphere Ionosphere Link Explorer (SMILE) is an ESA-CAS
joint mission. Primary goals are investigating the dynamic response of the
Earth's magnetosphere to the solar wind (SW) impact via simultaneous in situ
magnetosheath (MS) plasma and magnetic field measurements, X-Ray images of the
magnetosheath and magnetic cusps, and UV images of global auroral
distributions. Magnetopause (MP) deformations associated with MS high speed
jets (HSJs) under a quasi-parallel interplanetary magnetic field condition are
studied using a three-dimensional (3-D) global hybrid simulation. Soft X-ray
intensity calculated based on both physical quantities of solar wind proton and
oxygen ions is compared. We obtain key findings concerning deformations at the
MP: (1) MP deformations are highly coherent with the MS HSJs generated at the
quasiparallel region of the bow shock, (2) X-ray intensities estimated using
solar wind H+ and self-consistent O7+ ions are consistent with each other, (3)
Visual spacecraft are employed to check the discrimination ability for
capturing MP deformations on Lunar and polar orbits, respectively. The SMILE
spacecraft on the polar orbit could be expected to provide opportunities for
capturing the global geometry of the magnetopause in the equatorial plane. A
striking point is that SMILE has the potential to capture small-scale MP
deformations and MS transients, such as HSJs, at medium altitudes on its orbit
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Use of metal/uranium mixtures to explore data uncertainties
A table of k{sub {infinity}} values for three homogenized metal/{sup 235}U systems calculated using both MCNP and the SCALE code system was presented in Ref. 3. The homogenized metal/{sup 235} U ratios were selected such that the MCNP analyses for each mixture provided k{sub {infinity}} {approx_equal} 1.0. The metals considered were Al, Zr, and Fe. These simplified systems were created in an effort to ease an investigation of discrepant results obtained using MCNP and SCALE to analyze large, dry systems of metal-clad, highly enriched fuel assemblies. Reference 3 has received considerable attention at ORNL and elsewhere because the reported k{sub {infinity}} values varied by as much as 38% between the MCNP results and those of SCALE. The ORNL approach was to analyze the systems using a broad range of codes and data and to seek an understanding of the discrepancies by studying differences in the basic data and processing methods. The continuous-energy codes and data applied in the ORNL study were (1) MCNP, using ENDF/B-V, ENDF/B-VI, and LANL data evaluations, (2) VIM, using ENDF/B-V data, and (3) MONK, using a 8,200-point library based on UKNDL evaluations and a preliminary JEF library. The VIM code provides treatment of unresolved resonances; MCNP does not. The MONK analyses provided a result using both an independent code and independent data evaluations. Although accessing continuous-energy data typically requires the use of Monte Carlo codes, 1-D deterministic codes can be used to accurately calculate K{sub {infinity}} values using a variety of multigroup data libraries and processing methods. The multigroup codes used in the study were MC and the CSAS1X sequence of the SCALE system. Both systems provide problem-dependent resonance processing of cross-section data and available fine-group libraries were used for the analyses. Broad-group libraries were not studied in any depth because there were non-readily available for intermediate-energy systems
Analytic study of properties of holographic p-wave superconductors
In this paper, we analytically investigate the properties of p-wave
holographic superconductors in -Schwarzschild background by two
approaches, one based on the Sturm-Liouville eigenvalue problem and the other
based on the matching of the solutions to the field equations near the horizon
and near the asymptotic region. The relation between the critical
temperature and the charge density has been obtained and the dependence of the
expectation value of the condensation operator on the temperature has been
found. Our results are in very good agreement with the existing numerical
results. The critical exponent of the condensation also comes out to be 1/2
which is the universal value in the mean field theory.Comment: Latex, To appear in JHE
Inertial Mass of a Vortex in Cuprate Superconductors
We present here a calculation of the inertial mass of a moving vortex in
cuprate superconductors. This is a poorly known basic quantity of obvious
interest in vortex dynamics. The motion of a vortex causes a dipolar density
distortion and an associated electric field which is screened. The energy cost
of the density distortion as well as the related screened electric field
contribute to the vortex mass, which is small because of efficient screening.
As a preliminary, we present a discussion and calculation of the vortex mass
using a microscopically derivable phase-only action functional for the far
region which shows that the contribution from the far region is negligible, and
that most of it arises from the (small) core region of the vortex. A
calculation based on a phenomenological Ginzburg-Landau functional is performed
in the core region. Unfortunately such a calculation is unreliable, the reasons
for it are discussed. A credible calculation of the vortex mass thus requires a
fully microscopic, non-coarse grained theory. This is developed, and results
are presented for a s-wave BCS like gap, with parameters appropriate to the
cuprates. The mass, about 0.5 per layer, for magnetic field along the
axis, arises from deformation of quasiparticle states bound in the core, and
screening effects mentioned above. We discuss earlier results, possible
extensions to d-wave symmetry, and observability of effects dependent on the
inertial mass.Comment: 27 pages, Latex, 3 figures available on request, to appear in
Physical Review
Free flux flow resistivity in strongly overdoped high-T_c cuprate; purely viscous motion of the vortices in semiclassical d-wave superconductor
We report the free flux flow (FFF) resistivity associated with a purely
viscous motion of the vortices in moderately clean d-wave superconductor
Bi:2201 in the strongly overdoped regime (T_c=16K) for a wide range of the
magnetic field in the vortex state. The FFF resistivity is obtained by
measuring the microwave surface impedance at different microwave frequencies.
It is found that the FFF resistivity is remarkably different from that of
conventional s-wave superconductors. At low fields (H<0.2H_c2) the FFF
resistivity increases linearly with H with a coefficient which is far larger
than that found in conventional s-wave superconductors. At higher fields, the
FFF resistivity increases in proportion to \sqrt H up to H_c2. Based on these
results, the energy dissipation mechanism associated with the viscous vortex
motion in "semiclassical" d-wave superconductors with gap nodes is discussed.
Two possible scenarios are put forth for these field dependence; the
enhancement of the quasiparticle relaxation rate and the reduction of the
number of the quasiparticles participating the energy dissipation in d-wave
vortex state.Comment: 9 pages 7 figures, to appear in Phys. Rev.
Metal-macrofauna interactions determine microbial community structure and function in copper contaminated sediments
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