2,203 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
Investigating a Global Collapsing Hub-Filament Cloud G326.611+0.811
We present the dynamics study toward the G326.611+0.811 (G326)
hub-filament-system (HFS) cloud using the new APEX observations of both
CO and CO (J = 2-1). The G326 HFS cloud constitutes a central hub
and at least four hub-composing filaments that are divided into a major branch
of filaments (F1, and F2) and a side branch (F3-F5). The cloud holds ongoing
high-mass star formation as characterised by three massive dense clumps (i.e.,
370-1100 and 0.14-0.16 g cm for C1-C3) with the high
clump-averaged mass infalling rates ( yr) within
in the major filament branch, and the associated point sources bright at 70
m typical of young protostars. Along the five filaments, the velocity
gradients are found in both CO and CO (J = 2-1) emission,
suggesting that the filament-aligned gravitational collapse toward the central
hub (i.e., C2) is being at work for high-mass star formation therein. Moreover,
a periodic velocity oscillation along the major filament branch is revealed in
both CO and CO (J = 2-1) emission with a characteristic
wavelength of 3.5 pc and an amplitude of 0.31-0.38 km s. We
suggest that this pattern of velocity oscillation in G326 could arise from the
clump-forming gas motions induced by gravitational instability. Taking into
account the prevalent velocity gradients, the fragmentation of the major branch
of filaments, and the ongoing collapse of the three massive dense clumps, it is
indicative that G326 is a HFS undergoing global collapse.Comment: 21 pages, 13 figures, 2 tables, Accepted for publication in Ap
Differences in regional homogeneity between patients with Crohn's disease with and without abdominal pain revealed by resting-state functional magnetic resonance imaging
Abnormal pain processing in the central nervous system may be related to abdominal pain in patients with Crohn's disease (CD). The purpose of this study was to investigate changes in resting-state brain activity in patients with CD in remission and its relationship with the presence of abdominal pain. Twenty-five patients with CD and with abdominal pain, 25 patients with CD and without abdominal pain, and 32 healthy subjects were scanned using a 3.0-T functional magnetic resonance imaging scanner. Regional homogeneity (ReHo) was used to assess resting-state brain activity. Daily pain scores were collected 1 week before functional magnetic resonance imaging. We found that patients with abdominal pain exhibited lower ReHo values in the insula, middle cingulate cortex (MCC), and supplementary motor area and higher ReHo values in the temporal pole. In contrast, patients without abdominal pain exhibited lower ReHo values in the hippocampal/parahippocampal cortex and higher ReHo values in the dorsomedial prefrontal cortex (all P < 0.05, corrected). The ReHo values of the insula and MCC were significantly negatively correlated with daily pain scores for patients with abdominal pain (r = -0.53, P = 0.008 and r = -0.61, P = 0.002, respectively). These findings suggest that resting-state brain activities are different between remissive patients with CD with and without abdominal pain and that abnormal activities in insula and MCC are closely related to the severity of abdominal pain
<i>ABCA4</i> Gene Screening in a Chinese Cohort With Stargardt Disease:Identification of 37 Novel Variants
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