在亚泊松泵浦统计和压缩真空条件下多单光子关联辐射光子双稳态

证明了亚泊松泵浦及原子的相干性可使多单光子双稳态的光场噪声降低，但不能产生光场的压缩效应。若向腔中注入压缩真空，可在双稳态的上支产生几乎完全的光子数压缩效应。同时还证明，双稳态临界合作系数与原子的相干性及集居数都有关。

Investigating the role of^(99m)Tc-TRODAT-1 SPECT imaging in idiopathic Parkinson's disease

Objective:To investigate the role of ^(99m)Tc-TRODAT-1 SPECT in diagnosis and assessing severity of idiopathicParkinson's disease(PD).Methods:Thirty-eight patients with primary,tentative diagnosis of PD and eighteen age-matchednormal controls were studied with ^(99m)Tc-TRODAT-1 SPECT imaging.The regions of interests(ROIs)were drawn manually oncerebellum(CB),occipital cortex(OC)and three transverse plane slice-views of striatums,the semiquantitative BG(back-ground)/[(OC+CB)/2]were then calculated.Results:A lower uptake of ^(99m)Tc-TRODAT-1 in striatums were displayed inthirty-six out of thirty-eight PD patients by visual inspection,compared to controls.In twenty-four PD cases with HYS(Hoehn andYahr scale)stage Ⅰ,a greater loss of DAT uptake was found in striatum and its subregions contralateral striatum to the affectedlimbs than in the same regions of the controls,although the striatal uptake was bilaterally reduced.Using Spearman correlationanalysis showed that the reduction of the uptake ratios significantly correlated with the UPDRS in striatum and all its subregions inthe PD group(P<0.05),a similar change was also found in the putamen by using the rating scale of Hoehn and Yahr (P<0.05).However,analysis of variance(ANOVA)did not show any relationship between the decreasing uptake of ^(99m)Tc-TRODAT-1 andincreasing severity of PD patients,although the specific uptake of ^(99m)Tc-TRODAT-1 was continuously decreased in the striatumby visual inspection with the progress of PD from HYS stage Ⅰ to Ⅲ.Conclusion:^(99m)Tc-TRODAT-1 SPECT imaging may serve asa useful method for improving the correct diagnosis of PD.In assessing the role of ^(99m)Tc-TRODAT-1 SPECT in disease severity ofPD,UPDRS can offer a comprehensive index,although the Hoehn and Yahr assessment may be available in part.

One-Step Generation of Scalable Multiparticle Entanglement for Hot Ions Driven by a Standing-Wave Laser

An alternative scheme is proposed for one-step generation of multiparticle cluster state with trapped ionsin thermal motion.In this scheme,the ions are simultaneously illuminated by a standing-wave laser tuned to the carrier.During the operations,the vibrational mode is virtually excited,thus the quantum operations are insensitive to theheating.It is shown that the high fidelity multiparticle entanglement could be generated in just one step even includingthe small fluctuations of parameters.In addition,the ion does not need to be exactly positioned at the node of thestanding wave,which is also important from the viewpoint of experiment.

The entanglement evolution of two coupling two-level atoms interacting with a single-mode vacuum field in multiphoton Tavis-Cummings model

Using multipohton Tavis-Cummings model,the entanglement evolution of two coupling two-level atoms in Bell states interacting with a single-mode vacuum field is investigated by using negativity.The influences of coupling constants between atoms,the atomic initial states and the photon number of transition on the entanglement evolution of two coupling two-level atoms are discussed.The results obtained using the numerical method show that the entanglement of two atoms is related with coupling constants between atoms,the atomic initial states and the photon number of transition.The two-atom entanglement state will forever stay in the maximum entanglement state when the initial state is β11〉.When the initial state of two atoms is β01〉,the entanglement of two atoms displays periodic oscillation behavior.And its oscillation period decreases with increasing of coupling constant between atoms or the photon number of transition.On the other hand,when the initial state is β00〉 or β10〉,the entanglement of two atoms displays quasiperiodic oscillation behavior and its oscillation period decreases with increasing of coupling constant between atoms or the photon number of transition.

Single-polarization photonic crystal fibers with a multiplex structure

A new kind of single-polarization photonic crystal fiber(PCF) is proposed.Two kinds of multi-component glasses and the air are selected as working materials.Through using the full vector finite element method(FEM) and the perfectly matched layers(PML),the polarization-maintaining characteristic and the confinement loss of the fiber are analyzed,respectively.In addition,the single-polarization region of the fiber around 1.55 ìm is discussed.Numerical simulations show that the fiber maintains single-polarization operation within the wavelength range of 1.421-1.696μm.The birefringence can reach 6.988×10-3,and the confinement loss is as low as 0.012 dB/m when 7 layers of ring holes are arranged in the cladding at λ=1.55μm.