8,274 research outputs found
Spin filtering implemented through Rashba and weak magnetic modulations
We present two theoretical schemes for spin filters in one-dimensional
semiconductor quantum wires with spatially modulated Rashba spin-orbit coupling
(SOC) as well as weak magnetic potential. For case I, the SOC is periodic and
the weak magnetic potential is applied uniformly along the wire. Full spin
polarizations with opposite signs are obtained within two separated energy
intervals. For case II, the weak magnetic potential is periodic while the SOC
is uniform. An ideal negative/positive switching effect for spin polarization
is realized by tuning the strength of SOC. The roles of SOC, magnetic
potential, and their coupling on the spin filtering are analyzed.Comment: 4 pages, 4 figure
H\"older Stable Recovery of Time-Dependent Electromagnetic Potentials Appearing in a Dynamical Anisotropic Schr\"odinger Equation
We consider the inverse problem of H\"oldder-stably determining the time- and
space-dependent coefficients of the Schr\"odinger equation on a simple
Riemannian manifold with boundary of dimension from knowledge of the
Dirichlet-to-Neumann map. Assuming the divergence of the magnetic potential is
known, we show that the electric and magnetic potentials can be H\"older-stably
recovered from these data. Here we also remove the smallness assumption for the
solenoidal part of the magnetic potential present in previous results
Superfluid current disruption in a chain of weakly coupled Bose-Einstein Condensates
We report the experimental observation of the disruption of the superfluid
atomic current flowing through an array of weakly linked Bose-Einstein
condensates. The condensates are trapped in an optical lattice superimposed on
a harmonic magnetic potential. The dynamical response of the system to a change
of the magnetic potential minimum along the optical lattice axis goes from a
coherent oscillation (superfluid regime) to a localization of the condensates
in the harmonic trap ("classical" insulator regime). The localization occurs
when the initial displacement is larger than a critical value or, equivalently,
when the velocity of the wavepacket's center of mass is larger than a critical
velocity dependent on the tunnelling rate between adjacent sites.Comment: 8 pages, 4 figure
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