Shougang Zhang

cDNA cloning of heat shock proteins and their expression in the two phases of the migratory locust

The high population density of insects is often a stress factor. Insects synthesize heat shock proteins (Hsps) in response to the impacts of stress through molecular chaperone activity. Locust solitary and gregarious phases occur at low and high population density, respectively. In this study, we compare the expression profiles of the Hsp genes in the two phases of the migratory locust in an attempt to examine the role of Hsps in adaptation to high density populations. The full length cDNAs of Hsp20.5, 20.6, 20.7, 40, 70 and Hsp90 of the migratory locust were cloned and sequenced. The expressional differentiation of the six Hsps in mRNA levels between solitary and gregarious locusts was observed. Results from real‐time PCR indicate that the six Hsps are expressed throughout all developmental stages except in the early stage embryo. The expression levels of the six Hsps were significantly upregulated in gregarious locusts. The expressional variations among certain organs, such as the head, thorax and leg of fifth instar nymphs in gregarious locusts were also higher than those in solitary ones. These observations suggest that population density may be an important factor in determining Hsp expression in the locust.

Generation of Airy beams by four-wave mixing in Rubidium vapor cell

We report on an experimental generation of Airy beams by four-wave mixing (FWM) in atomic vapor cells. This is achieved by using a non-degenerate FWM process, which occurs with two Gaussian pump beams and one Airy signal beam in hot Rubidium vapor. After satisfying the phase matching condition, a FWM field with the profile of an Airy beam can be generated. In our experiment, the diffraction-free and self-healing behaviors of the generated FWM beam are examined. The results shown that the generated FWM beam is an Airy beam. The nonlinear generation process can be extended to other configurations in the atomic medium, which will be useful for manipulation and application of Airy beams in atomic systems.

Measurements of bremsstrahlung spectra of Lanzhou ECR Ion Source No. 3 (LECR3)

In order to diagnose the electron cyclotron resonance (ECR) plasma, electron bremsstrahlung spectra were measured by a HPGe detector on Lanzhou ECR Ion Source No. 3 at IMP. The ion source was operated with argon under various working conditions, including different microwave power, mixing gas, extraction high voltage (HV), and so on. Some of the measured spectra are presented in this article. The dependence of energetic electron population on mixing gas and extraction HV is also described. Additionally, we are looking forward to further measurements on SECRAL (Superconducting ECR Ion Source with Advanced design at Lanzhou).

Transfer and conversion of images based on EIT in atom vapor.

Transfer and conversion of images between different wavelengths or polarization has significant applications in optical communication and quantum information processing. We demonstrated the transfer of images based on electromagnetically induced transparency (EIT) in a rubidium vapor cell. In experiments, a 2D image generated by a spatial light modulator is used as a coupling field, and a plane wave served as a signal field. We found that the image carried by coupling field could be transferred to that carried by signal field, and the spatial patterns of transferred image are much better than that of the initial image. It also could be much smaller than that determined by the diffraction limit of the optical system. We also studied the subdiffraction propagation for the transferred image. Our results may have applications in quantum interference lithography and coherent Raman spectroscopy.

Influence of human activity and monsoon dynamics on spatial and temporal hydrochemistry in tropical coastal waters (Sanya Bay, South China Sea)

Human activities and oceanic influences like mixing and/or upwelling define the hydrochemical and biological characteristics of coastal regions. In Sanya Bay, northern South China Sea, the balance between these two influences on spatial and temporal scales is poorly understood. The influence from human activities was due to discharge from Sanya River, whereas the most important marine influence was related to seasonal changes in hydrodynamics. Spatial differences (p<0.05) in total nitrogen (TN) and chlorophyll-a (Chl-a) were observed. Seasonal differences were observed for temperature and nutrients. Human activities are the dominant factor influemcing hydrochemistry in the inner bay. This region exhibited the maximum influence of discharge from Saya River as estimated by higher nutrient levels. Oceanic influences like upwelling and mixing caused by monsoons are the dominant factors influencing hydrochemistry in the central and outer bay. Both human activities and oceanic influences play important roles in coastal ecosystems in Sanya Bay. This study has defined these characteristics so that better management policies can be enacted.

Demonstration of quantum synchronization based on second-order quantum coherence of entangled photons

Based on the second-order quantum interference between frequency entangled photons that are generated by parametric down conversion, a quantum strategic algorithm for synchronizing two spatially separated clocks has been recently presented. In the reference frame of a Hong-Ou-Mandel (HOM) interferometer, photon correlations are used to define simultaneous events. Once the HOM interferometer is balanced by use of an adjustable optical delay in one arm, arrival times of simulta- neously generated photons are recorded by each clock. The clock offset is determined by correlation measurement of the recorded arrival times. Utilizing this algorithm, we demonstrate a proof-of-principle experiment for synchronizing two clocks separated by 4 km fiber link. A minimum timing stability of 0.44 ps at averaging time of 16000 s is achieved with an absolute time accuracy of 73.2 ps. The timing stability is verified to be limited by the correlation measurement device and ideally can be better than 10 fs. Such results shine a light to the application of quantum clock synchronization in the real high-accuracy timing system.

Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps

Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures.

Demonstration of CNOT gate with Laguerre Gaussian beams via four-wave mixing in atom vapor

We present an experimental study of controlled-NOT (CNOT) gate through four-wave mixing (FWM) process in a Rubidium vapor cell. A degenerate FWM process in a two level atomic system is directly excited by a single diode laser, where backward pump beam and probe beam are Laguerre Gaussian mode. By means of photons carrying orbital angular momentum, we demonstrate the ability to realize CNOT gate with topological charges transformation in this nonlinear process. The fidelity of CNOT gate for a superposition state with different topological charge reaches about 97% in our experiment.

Fidelity of light storage in warm atomic gases at different storage time

The fidelity of light with arbitrary polarizations stored in a warm 87Rb atomic vapor at different storage time is studied. The exponential decay of regeneration efficiency with the storage time is observed and a detectable signal at 300-¹s storage time is still existed. The storage fidelity at different storage time is well maintained in our experiment.

Spin-orbit-coupled Bose-Einstein condensates held under a toroidal trap

We study a quasispin-