468 research outputs found
Realization of Two-Dimensional Spin-orbit Coupling for Bose-Einstein Condensates
Cold atoms with laser-induced spin-orbit (SO) interactions provide intriguing
new platforms to explore novel quantum physics beyond natural conditions of
solids. Recent experiments demonstrated the one-dimensional (1D) SO coupling
for boson and fermion gases. However, realization of 2D SO interaction, a much
more important task, remains very challenging. Here we propose and
experimentally realize, for the first time, 2D SO coupling and topological band
with Rb degenerate gas through a minimal optical Raman lattice scheme,
without relying on phase locking or fine tuning of optical potentials. A
controllable crossover between 2D and 1D SO couplings is studied, and the SO
effects and nontrivial band topology are observed by measuring the atomic cloud
distribution and spin texture in the momentum space. Our realization of 2D SO
coupling with advantages of small heating and topological stability opens a
broad avenue in cold atoms to study exotic quantum phases, including the
highly-sought-after topological superfluid phases.Comment: 27 pages, 5 figure
Stability of Excited Dressed States with Spin-Orbit Coupling
We study the decay behaviors of ultracold atoms in metastable states with
spin-orbit coupling (SOC), and demonstrate that there are two SOC-induced decay
mechanisms. One arises from the trapping potential and the other is due to
interatomic collision. We present general schemes for calculating decay rates
from these two mechanisms, and illustrate how the decay rates can be controlled
by experimental parameters.We experimentally measure the decay rates over a
broad parameter region, and the results agree well with theoretical
calculations. This work provides an insight for both quantum simulation
involving metastable dressed states and studies on few-body problems with SO
coupling.Comment: 4.5 pages, 4 figures, the latest versio
Solving Solar Neutrino Puzzle via LMA MSW Conversion
We analyze the existing solar neutrino experiment data and show the allowed
regions. The result from SNO's salt phase itself restricts quite a lot the
allowed region's area. Reactor neutrinos play an important role in determining
oscillation parameters. KamLAND gives decisive conclusion on the solution to
the solar neutrino puzzle, in particular, the spectral distortion in the 766.3
Ty KamLAND data gives another new improvement in the constraint of solar
MSW-LMA solutions. We confirm that at 99.73% C.L. the high-LMA solution is
excluded.Comment: 6 eps figure
Changes and Relationship of PAF and TNF in Rats with Myocardial Ischaemia and Reperfusion Injury
In this study it is reported that: (1) the levels of blood
platelet-activating factor and serum tumour necrosis factor
significantly increased after coronary ligation and reperfusion,
compared with sham-ligated controls, in an anaesthetized rat model;
(2) compared with vehicle controls, pretreatment with the PAF
antagonist BN 50739 (10 mg/kg, i.v.) produced significant
decreases in infarct size (from 29.6 ± 4.0% to 22.4
± 2.1%, p < 0.05 after 3 h ligation, and from
28.5 ± 9.5% to 10.5 ± 4.5%,
p < 0.01 after 4 h reperfusion) and the level of serum TNF (from 10.4
± 7.7 U/ml to 3.9 ± 4.8 U/ml, p < 0.05); and (3) a significan positive correlation was found between the
level of blood PAF or serum TNF and infarct size. The present
results indicate that PAF and TNF may be important mediators
involved in myocardial ischaemia and reperfusion injury, and that
PAF antagonists may exert a protective effect on ischaemic or
reperfused myocardium by inhibiting the interaction of PAF and TNF
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