16,131 research outputs found
Intense terahertz laser fields on a quantum dot with Rashba spin-orbit coupling
We investigate the effects of the intense terahertz laser field and the
spin-orbit coupling on single electron spin in a quantum dot. The laser field
and the spin-orbit coupling can strongly affect the electron density of states
and can excite a magnetic moment.
The direction of the magnetic moment depends on the symmetries of the system,
and its amplitude can be tuned by the strength and frequency of the laser field
as well as the spin-orbit coupling.Comment: 5 pages, 4 figures, to be published in J. Appl. Phy
The NSNS High Energy Beam Transport Line
In the National Spallation Neutron Source (NSNS) design, a 180 meter long
transport line connects the 1 GeV linac to an accumulator ring. The linac beam
has a current of 28 mA, pulse length of 1 ms, and 60 Hz rep rate. The high
energy transport line consists of sixteen 60 degrees FODO cells, and
accommodates a 90 degrees achromatic bend, an energy compressor, collimators,
part of injection system, and enough diagnostic devices to measure the beam
quality before injection. To reduce the uncontrolled beam losses, this line has
nine beam halo scrapers and very tight tolerances on both transverse and
longitudinal beam dynamics under space charge conditions. The design of this
line is presented.Comment: 3 pages, transfer line desig
Spin-roton excitations in the cuprate superconductors
We identify a new kind of elementary excitations, spin-rotons, in the doped
Mott insulator. They play a central role in deciding the superconducting
transition temperature Tc, resulting in a simple Tc formula,Tc=Eg/6, with Eg as
the characteristic energy scale of the spin rotons. We show that the degenerate
S=1 and S=0 rotons can be probed by neutron scattering and Raman scattering
measurements, respectively, in good agreement with the magnetic resonancelike
mode and the Raman A1g mode observed in the high-Tc cuprates.Comment: 10 pages, 9 figure
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