1,212 research outputs found
Spin-Hall Effect in A Symmetric Quantum Wells by A Random Rashba Field
Changes dopant ion concentrations in the sides of a symmetric quantum well
are known to create a random Rashba-type spin-orbit coupling. Here we
demonstrate that, as a consequence, a finite size spin-Hall effect is also
present. Our numerical algorithm estimates the result of the Kubo formula for
the spin-Hall conductivity, by using a tight-binding approximation of the
Hamiltonian in the framework of a time-dependent Green's function formalism,
well suited for very large systems.Comment: 4 pages, 4 figures in eps forma
Spin Hall Effect in a Symmetric Quantum Well by a Random Rashba Field
Dopant ion concentrations in the sides of a symmetric quantum well are known to create a random Rashba-type spin-orbit coupling. Here, we demonstrate that, as a consequence, a ïŹnite size spin Hall effect is also present. Our numerical algorithm estimates the result of the Kubo formula for the spin Hall conductivity by using a tight-binding approximation of the Hamiltonian in the framework of a time-dependent Greenâs function formalism well suited for very large systems
A parallel Algorithm for Determining Orientations of Biological Macro- molecules Imaged by Electron Microscopy
Szeg\"o kernel asymptotics and Morse inequalities on CR manifolds
We consider an abstract compact orientable Cauchy-Riemann manifold endowed
with a Cauchy-Riemann complex line bundle. We assume that the manifold
satisfies condition Y(q) everywhere. In this paper we obtain a scaling
upper-bound for the Szeg\"o kernel on (0, q)-forms with values in the high
tensor powers of the line bundle. This gives after integration weak Morse
inequalities, analogues of the holomorphic Morse inequalities of Demailly. By a
refined spectral analysis we obtain also strong Morse inequalities which we
apply to the embedding of some convex-concave manifolds.Comment: 40 pages, the constants in Theorems 1.1-1.8 have been modified by a
multiplicative constant 1/2 ; v.2 is a final updat
Macrodimers: ultralong range Rydberg molecules
We study long range interactions between two Rydberg atoms and predict the
existence of ultralong range Rydberg dimers with equilibrium distances of many
thousand Bohr radii. We calculate the dispersion coefficients ,
and for two rubidium atoms in the same excited level , and find
that they scale like , and , respectively. We show that
for certain molecular symmetries, these coefficients lead to long range
potential wells that can support molecular bound levels. Such macrodimers would
be very sensitive to their environment, and could probe weak interactions. We
suggest experiments to detect these macrodimers.Comment: 4 pages, submitted to PR
Low energy atomic collision with dipole interactions
We apply quantum defect theory to study low energy ground state atomic
collisions including aligned dipole interactions such as those induced by an
electric field. Our results show that coupled even () relative orbital
angular momentum partial wave channels exhibit shape resonance structures while
odd () channels do not. We analyze and interpret these resonances within the
framework of multichannel quantum defect theory (MQDT).Comment: 27 pages, 17 figures, an inadvertent typo correcte
High-precision calculations of dispersion coefficients, static dipole polarizabilities, and atom-wall interaction constants for alkali-metal atoms
The van der Waals coefficients for the alkali-metal atoms from Na to Fr
interacting in their ground states, are calculated using relativistic ab initio
methods. The accuracy of the calculations is estimated by also evaluating
atomic static electric dipole polarizabilities and coefficients for the
interaction of the atoms with a perfectly conducting wall. The results are in
excellent agreement with the latest data from ultra-cold collisions and from
studies of magnetic field induced Feshbach resonances in Na and Rb. For Cs we
provide critically needed data for ultra-cold collision studies
Prospects for p-wave paired BCS states of fermionic atoms
We present theoretical prospects for creating p-wave paired BCS states of
magnetic trapped fermionic atoms. Based on our earlier proposal of using dc
electric fields to control both the strength and anisotropic characteristic of
atom-atom interaction and our recently completed multi-channel atomic collision
calculations we discover that p-wave pairing with K and Rb
in the low field seeking maximum spin polarized state represent excellent
choices for achieving superfluid BCS states; and may be realizable with current
technology in laser cooling, magnetic trapping, and evaporative/sympathetic
cooling, provided the required strong electric field can be applied. We also
comment on the prospects of similar p-wave paired BCS states in Li, and
more generally on creating other types exotic BCS states. Our study will open a
new area in the vigorous pursuit to create a quantum degenerate fermionic atom
vapor.Comment: to be publishe
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