22,150 research outputs found
Universal scaling behavior of the single electron box in the strong tunneling limit
We perform a numerical analysis of recently proposed scaling functions for
the single electron box. Specifically, we study the ``magnetic'' susceptibility
as a function of tunneling conductance and gate charge, and the effective
charging energy at zero gate charge as a function of tunneling conductance in
the strong tunneling limit. Our Monte Carlo results confirm the accuracy of the
theoretical predictions.Comment: Published versio
High-precision Atomic Physics Laboratories in Space: White Dwarfs and Subdwarfs
The 21st European Workshop on White Dwarfs was held in Austin, TX from July 23rd to 27th of 2018Stellar atmospheres are prime laboratories to determine
atomic properties of highly ionized species.
Reliable opacities are crucial ingredients for the
calculation of stellar atmospheres of white dwarfs
and subdwarfs. A detailed investigation on the
precision of many iron-group oscillator strengths
is still outstanding. To make progress, we used
the Hubble Space Telescope Imaging Spectrograph
to measure high-resolution spectra of three hot
subdwarfs that exhibit extremely high iron-group
abundances. The predicted relative strengths of
the identified lines are compared with the observations
to judge the quality of Kurucz’s line data
and to determine correction factors for abundance
determinations of the respective elements.Astronom
Interference in presence of Dissipation
We study a particle on a ring in presence of various dissipative
environments. We develop and solve a variational scheme assuming low frequency
dominance. We analyze our solution within a renormalization group (RG) scheme
to all orders which reproduces a 2 loop RG for the Caldeira-Legget environment.
In the latter case the Aharonov-Bohm (AB) oscillation amplitude is exponential
in -R^2 where R is the ring's radius. For either a charge or an electric dipole
coupled to a dirty metal we find that the metal induces dissipation, however
the AB amplitude is ~ R^{-2} for large R, as for free particles. Cold atoms
with a large electric dipole may show a crossover between these two behaviors.Comment: 5 pages, added motivations and reference
Preserving the measure of compatibility between quantum states
In this paper after defining the abstract concept of compatibility-like
functions on quantum states, we prove that every bijective transformation on
the set of all states which preserves such a function is implemented by an
either unitary or antiunitary operator.Comment: 11 pages, submitted for publicatio
Spectral Types of Planetary Host Star Candidates: Two New Transiting Planets?
Recently, 46 low-luminosity object transits were reported from the Optical
Gravitational Lensing Experiment. Our follow-up spectroscopy of the 16 most
promising candidates provides a spectral classification of the primary.
Together with the radius ratio from the transit measurements, we derived the
radii of the low-luminosity companions. This allows to examine the possible
sub-stellar nature of these objects. Fourteen of them can be clearly identified
as low-mass stars. Two objects, OGLE-TR-03 and OGLE-TR-10 have companions with
radii of 0.15 R_sun which is very similar to the radius of the transiting
planet HD209458B. The planetary nature of these two objects should therefore be
confirmed by dynamical mass determinations.Comment: 4 pages, 3 figures, accepted for publication by A&A Letter
Magnetoresistance oscillations in GaAs/AlGaAs superlattices subject to in-plane magnetic fields
The MBE-grown GaAs/AlGaAs superlattice with Si-doped barriers has been used
to study a 3D-2D transition under the influence of the in-plane component of
applied magnetic field. The longitudinal magnetoresistance data measured in
tilted magnetic fields have been interpreted in terms of a simple tight-binding
model. The data provide values of basic parameters of the model and make it
possible to reconstruct the superlattice Fermi surface and to calculate the
density of states for the lowest Landau subbands. Positions of van Hove
singularities in the DOS agree excellently with magnetoresistance oscillations,
confirming that the model describes adequately the magnetoresistance of
strongly coupled semiconductor superlattices.Comment: 4 pages, 3 figures, elsart/PHYEAUTH macros; presented on the EP2DS-16
Conference in Albuquerque, New Mexico USA. To be published in Physica
Lowering of surface melting temperature in atomic clusters with a nearly closed shell structure
We investigate the interplay of particle number, N, and structural properties
of selected clusters with N=12 up to N=562 by employing Gupta potentials
parameterized for Aluminum and extensive Monte-Carlo simulations. Our analysis
focuses on closed shell structures with extra atoms. The latter can put the
cluster under a significant stress and we argue that typically such a strained
system exhibits a reduced energy barrier for (surface) diffusion of cluster
atoms. Consequently, also its surface melting temperature, T_S, is reduced, so
that T_S separates from and actually falls well below the bulk value. The
proposed mechanism may be responsible for the suppression of the surface
melting temperature observed in a recent experiments.Comment: 9 pages, 7 figures, 1 table, REVTeX 4; submitted to Phys.Rev.
Simulation of seismic events induced by CO2 injection at In Salah, Algeria
Date of Acceptance: 18/06/2015 Acknowledgments The authors would like to thank the operators of the In Salah JV and JIP, BP, Statoil and Sonatrach, for providing the data shown in this paper, and for giving permission to publish. Midland Valley Exploration are thanked for the use of their Move software for geomechanical restoration. JPV is a Natural Environment Research Council (NERC) Early Career Research Fellow (Grant NE/I021497/1) and ALS is funded by a NERC Partnership Research Grant (Grant NE/I010904).Peer reviewedPublisher PD
Quantum Mechanics as a Framework for Dealing with Uncertainty
Quantum uncertainty is described here in two guises: indeterminacy with its
concomitant indeterminism of measurement outcomes, and fuzziness, or
unsharpness. Both features were long seen as obstructions of experimental
possibilities that were available in the realm of classical physics. The birth
of quantum information science was due to the realization that such
obstructions can be turned into powerful resources. Here we review how the
utilization of quantum fuzziness makes room for a notion of approximate joint
measurement of noncommuting observables. We also show how from a classical
perspective quantum uncertainty is due to a limitation of measurability
reflected in a fuzzy event structure -- all quantum events are fundamentally
unsharp.Comment: Plenary Lecture, Central European Workshop on Quantum Optics, Turku
2009
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