3,849 research outputs found
Symplectic Geometry on Quantum Plane
A study of symplectic forms associated with two dimensional quantum planes
and the quantum sphere in a three dimensional orthogonal quantum plane is
provided. The associated Hamiltonian vector fields and Poissonian algebraic
relations are made explicit.Comment: 12 pages, Late
Berry's Phases of Ground States of Interacting Spin-One Bosons: Chains of Monopoles and Monosegments
We study Berry's connection potentials of many-body ground states of spin-one
bosons with antiferromagnetic interactions in adiabatically varying magnetic
fields. We find that Berry's connection potentials are generally determined by,
instead of usual singular monopoles, linearly positioned monosegments each of
which carries one unit of topological charge; in the absence of a magnetic
field gradient this distribution of monosegments becomes a linear chain of
monopoles. Consequently, Berry's phases consist of a series of step functions
of magnetic fields; a magnetic field gradient causes rounding of these
step-functions. We also calculate Berry's connection fields, profiles of
monosegments and show that the total topological charge is conserved in a
parameter space
Controlling Excitations Inversion of a Cooper Pair Box Interacting with a Nanomechanical Resonator
We investigate the action of time dependent detunings upon the excitation
inversion of a Cooper pair box interacting with a nanomechanical resonator. The
method employs the Jaynes-Cummings model with damping, assuming different decay
rates of the Cooper pair box and various fixed and t-dependent detunings. It is
shown that while the presence of damping plus constant detunings destroy the
collapse/revival effects, convenient choices of time dependent detunings allow
one to reconstruct such events in a perfect way. It is also shown that the mean
excitation of the nanomechanical resonator is more robust against damping of
the Cooper pair box for convenient values of t-dependent detunings.Comment: 11 pages, 5 figure
Composition dependence of electronic structure and optical properties of Hf1-xSixOy gate dielectrics
Copyright © 2008 American Institute of Physics. This article is copyrighted as indicated in the article. Reuse of AIP content is subject to the terms at: http://scitation.aip.org/termsconditionsComposition-dependent electronic structure and optical properties of Hf1−xSixOy 0.1 x 0.6 gate
dielectrics on Si at 450 °C grown by UV-photo-induced chemical vapor deposition UV-CVD have
been investigated via x-ray photoemission spectroscopy and spectroscopy ellipsometry SE . By
means of the chemical shifts in the Hf 4f, Si 2p, and O 1s spectra, the Hf–O–Si bondings in the
as-deposited films have been confirmed. Analyses of composition-dependent band alignment of
Hf1−xSixOy / Si gate stacks have shown that the valence band VB offset Ev demonstrates little
change; however, the values of conduction band offset Ec increase with the increase in the silicon
atomic composition, resulting from the increase in the separation between oxygen 2p orbital VB
state and antibonding d states intermixed of Hf and Si. Analysis by SE, based on the Tauc–Lorentz
model, has indicated that decreases in the optical dielectric constant and increase in band gap have
been observed as a function of silicon contents. Changes in the complex dielectric functions and
band gap Eg related to the silicon concentration in the films are discussed systematically. From the
band offset and band gap viewpoint, these results suggest that Hf1−xSixOy films provide sufficient
tunneling barriers for electrons and holes, making them promising candidates as alternative gate
dielectrics.National Natural Science Foundation of China and Royal Society U.K
The molecular systems composed of the charmed mesons in the doublet
We study the possible heavy molecular states composed of a pair of charm
mesons in the H and S doublets. Since the P-wave charm-strange mesons
and are extremely narrow, the future experimental
observation of the possible heavy molecular states composed of
and may be feasible if they really exist.
Especially the possible states may be searched for via the
initial state radiation technique.Comment: 42 pages, 4 tables, 31 figures. Improved numerical results and
Corrected typos
Propagation of strangelets in the Earth's atmosphere
A new model for the description of the behaviour of strangelets in the
Earth's atmosphere is presented. Strangelet fission induced by collision with
air nuclei is included. It is shown that strangelets with certain parameters of
initial mass and energy may reach depths near sea level, which can be examined
by ground-based experiments.Comment: 10 pages, 6 figure
Superconductivity in Fluorine-Arsenide Sr_{1-x}La_xFeAsF
Since the discovery of superconductivity\cite{1} at 26 K in oxy-pnictide
, enormous interests have been stimulated in the fields of
condensed matter physics and material sciences. Among the five different
structures in this broad type of superconductors\cite{2,3,4,5,6}, the ZrCuSiAs
structure has received special attention since the has been quickly
promoted to 55-56 K\cite{7,8,9,10,11} in fluorine doped oxy-pnictides REFeAsO
(RE = rare earth elements). The superconductivity can also be induced by
applying a high pressure to the undoped samples\cite{12,13}. The mechanism of
superconductivity in the FeAs-based system remains unclear yet, but it turns
out to be clear that any change to the structure or the building blocks will
lead to a change of the superconducting transition temperatures. In this
Letter, we report the fabrication of the new family of compounds, namely
fluorine-arsenides DvFeAsF (Dv = divalent metals) with the ZrCuSiAs structure
and with the new building block DvF instead of the REO (both the layers DvF and
REO have the combined cation state of "+1"). The undoped parent phase has a
Spin-Density-Wave like transition at about 173 K for SrFeAsF, 118 K for CaFeAsF
and 153 K for EuFeAsF. By doping electrons into the system the resistivity
anomaly associated with this SDW transition is suppressed and superconductivity
appears at 32 K in the fluorine-arsenide SrLaFeAsF (x = 0.4). Our
discovery here initiates a new method to obtain superconductors in the
FeAs-based system.Comment: 11 pages, 4 figures, typos added, references added, and one figure
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