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21.
通过优化了的氢化物发生—原子荧光法测定了7个省产绞股蓝及其根际土壤中As,Hg,Se三种元素的含量,研究结果表明:7个省产绞股蓝中As,Hg,Se的含量存在较大差异,但As和Hg两种重金属元素含量均低于《药用植物及制剂进出口绿色行业标准》中As和Hg的限量标准。Se元素含量同根际土壤中Se元素含量显示极显著相关性,故湖北恩施富硒区产绞股蓝中Se含量明显高于其他6省产绞股蓝。研究结果可以初步判定,绞股蓝中Se元素主要来源于土壤,而As和Hg元素的积累则不同于Se元素,还可能受到大气气溶胶的干、湿沉降等因素的影响。 相似文献
22.
Yu-chi Zhang Gang Li Peng-fei Zhang Jun-min Wang Tian-cai Zhang 《Frontiers of Physics in China》2009,4(2):190-197
Cavity QED, as a fundamental system and research field, not only illuminates the primary aspects of decoherence and coherence
in quantum dynamics, but also advances quantum information science. Manipulation of single atoms, in the context of cavity
QED, is the essential element and has been becoming a hot issue for the past two decades. In this review paper, we will concentrate
on the experimental aspects for manipulating the neutral atoms strongly coupled to a high-finesse cavity in the optical regime,
including atomic cooling and trapping, different configurations of atom transportation and the wide variety of quantum outgrowths
based on cavity QED, such as one atom laser, single photon source, etc. The cavity QED system at Shanxi University is briefly
introduced.
相似文献
23.
Shankari V. Rajagopal Kurt M. Fujiwara Ruwan Senaratne Kevin Singh Zachary A. Geiger David M. Weld 《Annalen der Physik》2017,529(8)
Ultracold atomic physics experiments offer a nearly ideal context for the investigation of quantum systems far from equilibrium. We describe three related emerging directions of research into extreme non‐equilibrium phenomena in atom traps: quantum emulation of ultrafast atom‐light interactions, coherent phasonic spectroscopy in tunable quasicrystals, and realization of Floquet matter in strongly‐driven lattice systems. We show that all three should enable quantum emulation in parameter regimes inaccessible in solid‐state experiments, facilitating a complementary approach to open problems in non‐equilibrium condensed matter. 相似文献
24.
Superexchange-mediated magnetization dynamics with ultracold alkaline-earth atoms in an optical lattice 下载免费PDF全文
Superexchange and inter-orbital spin-exchange interactions are key ingredients for understanding(orbital) quantum magnetism in strongly correlated systems and have been realized in ultracold atomic gases.Here we study the spin dynamics of ultracold alkaline-earth atoms in an optical lattice when the two exchange interactions coexist.In the superexchange interaction dominating regime,we find that the time-resolved spin imbalance shows a remarkable modulated oscillation,which can be attributed to the interplay between local and nonlocal quantum mechanical exchange mechanisms.Moreover,the filling of the long-lived excited atoms affects the collapse and revival of the magnetization dynamics.These observations can be realized in state-dependent optical lattices combined with the state-of-the-art advances in optical lattice clock spectroscopy. 相似文献
25.
通过增大样品进样量的方式,样品进样量是标准进样量的10-100倍,降低了汞的检出限,从而达到了无富集直接进样测定地表水中痕量汞.其检出限为0.008μg/L;浓度为0.05μg/L和0.10μg/L左右的有证标准物质测定均值分别为0.0483μg/L和0.1016μg/L,加标回收率为92.3%和95.2%.灵敏度高,精密度好,能达到准确定量Ⅰ类和Ⅱ类地表水汞(0.05μg/L以下)的要求.对汉江湖北段水样进行测定,在较洁净的地表水分析中,氧化还原处理后与酸化水样测定结果差异不大,处理后水样结果略微增大.建议对较洁净的地表水样品将氧化还原预处理步骤省略掉,直接进样. 相似文献
26.
J. Dabrowski J. Rożynek G.S. Anagnostatos 《The European Physical Journal A - Hadrons and Nuclei》2002,14(1):125-131
It is shown that among four models of the Nijmegen baryon-baryon interaction only model F --which leads to a repulsive potential
felt by the Σ hyperon inside the nucleus-- is consistent both with the analysis of Σ- atoms and of the (K
-,π) reactions. The Nijmegen models are used to determine the strong complex single-particle (s.p.) potential of Σ-, and to calculate the strong-interaction shifts and widths of the lowest observed levels of Σ- atoms. The results obtained with model F are in best agreement with the experimental data.
Received: 15 January 2002 / Accepted: 14 March 2002 相似文献
27.
Subodh R Shenoy 《Pramana》2002,58(2):385-397
We obtain the dynamics in number and phase difference, for Bose condensates that tunnel between two wells of a double-well
atomic trap, using the (nonlinear) Gross-Pitaevskii equation. The dynamical equations are of the canonical form for the two
conjugate variables, and the Hamiltonian corresponds to that of a momentum-shortened pendulum, supporting a richer set of tunneling oscillation modes than for a superconductor Josephson junction, that has a
fixed-length pendulum as a mechanical model. Novel modes include ‘inverted pendulum’ oscillations with an average angle of
π; and oscillations about a self-maintained population imbalance that we term ‘macroscopic quantum self-trapping’. Other systems
with this phase-number nonlinear dynamics include two-component (interconverting) condensates in a single harmonic trap, and
He3B superfluids in two containers connected by micropores. 相似文献
28.
Signals of ultracold plasma are observed by two-photon
ionization of laser-cooled caesium atoms in a magneto-optical trap.
Recombination of ions and electrons into Rydberg atoms during the
expansion of ultracold plasma is investigated by using
state-selective field ionization spectroscopy. The dependences of
recombination on initial electron temperature (1--70 K) and initial
ion density ($ \sim $10$^{10}$ cm$^{ - 3})$ are investigated. The
measured dependence on initial ion density is $N^{1.547\pm 0.004}$
at a delay time of 5 $\mu $s. The recombination rate rapidly
declines as initial electron temperature increases when delay time
is increased. The distributions of Rydberg atoms on different values
of principal quantum number $n$, i.e. $n=30$--60, at an initial
electron temperature of 3.3 K are also investigated. The main
experimental results are approximately explained by the three-body
recombination theory. 相似文献
29.
Dehua Wang Kaiyun Huang Shenglu Lin 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,54(3):699-706
The ionization of Rydberg hydrogen atoms near a metal surface at different scaled energies above the classical saddle point
energy has been discussed by using the semiclassical method. The results show that the atoms ionize by emitting a train of
electron pulses. In order to reveal the chaotic and escape dynamical properties of this system in detail, the sensitive dependence
of the ionization rate upon the scaled energy is discussed. As the scaled energy is close to the saddle point energy, the
ionization process of the hydrogen atom is nearly the same as the case of hydrogen atom in an electric field. There is only
a single pulse of electrons, with an exponentially decaying tail. With the increase of the scaled energy, the ionization rates
are similar to the case of the hydrogen atom in parallel electric and magnetic field, a series of electron pulses appear in
the ionization process. This is caused by classical chaos, which occurs for the metal surface. Our studies also suggest that
the metal surface can play the role of both the electric and the magnetic fields. Our theoretical analysis will be useful
for guiding experimental studies of the ionization of atoms near the metal surface. 相似文献
30.
A. Sanson M. Giarola E. Napolitani G. Impellizzeri V. Privitera A. Carnera G. Mariotto 《Journal of Raman spectroscopy : JRS》2013,44(5):665-669
The distribution profile of Al implanted in crystalline Ge has been investigated by micro‐Raman spectroscopy. Using different excitation laser lines, corresponding to different optical penetration depths, the Al concentration at different depths beneath the sample surface has been studied. We have found a strong correlation between the intensity of the Al–Ge Raman peak at ~370 cm−1, which is due to the local vibrational mode of substitutional Al atoms, and the carrier concentration profile, obtained by the spreading resistance profiling analysis. A similar connection has been also observed for both shape and position of the Ge–Ge Raman peak at ~300 cm−1. According to these experimental findings, we propose here a fast and nondestructive method, based on micro‐Raman spectroscopy under different excitation wavelengths, to estimate the carrier concentration profiles in Al‐implanted Ge. Copyright © 2013 John Wiley & Sons, Ltd. 相似文献