876 research outputs found
The Third Law of Quantum Thermodynamics in the Presence of Anomalous Couplings
The quantum thermodynamic functions of a harmonic oscillator coupled to a
heat bath through velocity-dependent coupling are obtained analytically. It is
shown that both the free energy and the entropy decay fast with the temperature
in relation to that of the usual coupling from. This implies that the
velocity-dependent coupling helps to ensure the third law of thermodynamics.Comment: 4 pages, 3 figures, 22 conference
Multiple images storage and frequency conversion in a cold atomic ensemble
The strong demand for quantum memory, a key building block of quantum
network, has inspired new methodologies and led to experimental progress for
quantum storage. The use of quantum memory for spatial multimode or image
storage could dramatically increase the channel bit-rate. Furthermore, quantum
memory that can store multiple optical modes would lead to higher efficiencies
in quantum communication and computation. Here, by using resonant tripod
electromagnetically induced transparency in a cold atomic ensemble, we
experimentally demonstrate multiple probes storage in frequency domain, where
two probe fields have discrete wavelengths and different spatial information.
In addition, by using different read-light, we realize frequency conversion of
retrieved images with high efficiency. Besides, our method could be used to
create a superposition of the images by realizing the function of a
beamsplitter. All advantages make our method useful in many fields including
quantum information, detection, imaging, sensing and even astrophysical
observation.Comment: Frequency-multiplexed image storage,high efficiency storage and
conversion for an imag
The Protective Effects of Curcumin on Obesity-Related Glomerulopathy Are Associated with Inhibition of Wnt/ β
The present study investigated the effects of curcumin, one of the most important active ingredients of turmeric, on podocyte injury in vitro and obesity-related glomerulopathy (ORG) in vivo. Cellular experiments in vitro showed that curcumin significantly antagonized leptin-induced downregulation of the mRNA and protein expression of podocyte-associated molecules including nephrin, podocin, podoplanin, and podocalyxin. Animal experiments in vivo showed that curcumin significantly reduced the body weight, Lee’s index, abdominal fat index, urinary protein excretion, and average glomerular diameter and significantly upregulated the mRNA and protein expressions of the above podocyte-associated molecules in ORG mice. Furthermore, the experiments in vitro and in vivo both displayed that curcumin could downregulate the mRNA and protein expressions of Wnt1, Wnt2b, Wnt6, and β-catenin and upregulate the phosphorylation level of β-catenin protein in podocytes and renal tissue. In conclusion, curcumin is able to alleviate the harmful reaction of leptin on podocytes and reduce the severity of ORG. The above protective effects are associated with the inhibition of Wnt/β-catenin signaling activation in podocytes
State transition of a non-Ohmic damping system in a corrugated plane
Anomalous transport of a particle subjected to non-Ohmic damping of the power
in a tilted periodic potential is investigated via Monte Carlo
simulation of generalized Langevin equation. It is found that the system
exhibits two relative motion modes: the locking state and the running state.
Under the surrounding of sub-Ohmic damping (), the particle should
transfer into a running state from a locking state only when local minima of
the potential vanish; hence the particle occurs a synchronization oscillation
in its mean displacement and mean square displacement (MSD). In particular, the
two motion modes are allowed to coexist in the case of super-Ohmic damping
() for moderate driving forces, namely, where exists double centers
in the velocity distribution. This induces the particle having faster
diffusion, i.e., its MSD reads . Our result shows that the effective power index
can be enhanced and is a nonmonotonic function of the
temperature and the driving force. The mixture effect of the two motion modes
also leads to a breakdown of hysteresis loop of the mobility.Comment: 7 pages,7 figure
High-dimensional frequency conversion in hot atomic system
One of the major difficulties in realizing a high-dimensional frequency
converter for conventional optical vortex (COV) stems from the difference in
ring diameter of COV modes with different topological charge numbers l. Here,
we implement a high-dimensional frequency convertor for perfect optical vortex
(POV) modes with invariant size through the four-wave mixing (FWM) process by
utilizing Bessel-Gaussian beams instead of Laguerre-Gaussian beams. The
measured conversion efficiency from 1530 nm to 795 nm is independent of l at
least in subspace of {-6,...,6}, and the achieved conversion fidelities for
two-dimensional (2D) superposed POV states exceed 97%. We further realize the
frequency conversion of 3D, 5D and 7D superposition states with fidelities as
high as 96.70%, 89.16% and 88.68%, respectively. The reported scheme is
implemented in hot atomic vapor, it's also compatible with the cold atomic
system and may find applications in high-capacity and long-distance quantum
communication
Detection of infrared light through stimulated four-wave mixing process
Infrared optical measurement has a wide range of applications in industry and
science, but infrared light detectors suffer from high costs and inferior
performance than visible light detectors. Four-wave mixing (FWM) process allows
detection in the infrared range by detecting correlated visible light. We
experimentally investigate the stimulated FWM process in a hot Rb atomic
vapor cell, in which a weak infrared signal laser at nm induces the FWM
process and is amplified and converted into a strong FWM light at nm, the
latter can be detected more easily. We find the optimized single- and
two-photon detunings by studying the dependence of the frequency of input laser
on the generated FWM light. What's more, the power gain increases rapidly as
the signal intensity decreases, which is consistent with our theoretical
analysis. As a result, the power gain can reach up to 500 at a signal laser
power of W and the number of detected photons increased by a factor of
250. Finally, we experimentally prove that our amplification process can work
in a broad band in the frequency domain by exploring the response rate of our
stimulated FWM process.Comment: 4 figure
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