我校刘振鹏教授已获可喜成果

物理系理论物理教研室刘振鹏教授,数年如一日始终坚持“一维化氢原子波动方程及其应用”的研究方向,经努力,已在英国《物理学报》、美国《物理评论》、《半导体学报》、《中国物理》等刊物上发表文章近十篇。特别是发表于美国《物理评论》（Phys Rev）B28 4413（1983）的“半无限空间中的氢原子”及英国《物理学报》（J.Phys）C18691（1985）的“在GaAs—Ga1-xAlxAs量子阱中的类氢杂质态”两篇论文,就其理论价值上看,他发现了在不同平面边界条件下,氢原子解之间的横向联系及转化趋势,并用他提出的氢原子薛定谔方程的一组化方法,沟通了这种联系,它可以重现三维解、Levine解和二维解,因此是继氢原子三维解（Schro dinger 1926）二维解（Elliot 1963）和Levine解（Levine 1965）之后,有关氢原子解的性质的重大发现。

Characteristics of Thermally-Induced Near-Surface Flows over An Enclosed Crater: Observations of the Meteor Crater Experiment(METCRAX)

Meteorological measurements of the Meteor Crater Experiment(METCRAX) were used to analyze the characteristics of the thermally-induced flows over an enclosed crater(Arizona, USA). Despite its relatively small size, this crater acts as an effective wind shelter. Daytime upslope winds and nocturnal downslope flows are regularly observed on its west/east sidewalls. The times of diurnal wind-direction shift(i.e., around sunrise and sunset) were slightly mismatched between the sites based on the east and west sidewalls, owing to the crater's shadowing effects. Under conditions of relatively weak synoptic forcing, the nocturnal downslope flows prevail throughout the night, despite quite a low wind velocity near the surface. ?

Thermal Entanglement in Two-Qutrit Heisenberg XX Chain with Different Dzyaloshinskii-Moriya Interaction and Nonuniform Magnetic Field

The effects of the different Dzyaloshinskii-Moriya （DM） interaction on thermal entanglement of a two-qutrit Heisenberg XX spin chain in a nonuniform magnetic field are investigated. Our results imply that the x-component DM interaztion plays a central role in enhancing quantum entanglement and it has a higher critical temperature than the z-component DM interaction. The entanglement can be tunable controlled by changing the multiple of the magnetic fields B1 and B2. Also we found that different DM interaction are competitive to each other in some conditions.

Quantum discord in the three-spin XXZ chain with Dzyaloshinskii-Moriya interaction

The quantum discord(QD) of a three-qubit Heisenberg XXZ system with the Dzyaloshinskii-Moriya(DM) interaction parameter is investigated,and the three-qubit QD under Ornstein-Uhlenbeck noise is calculated.We find that both DM interaction parameter D z and anisotropic parameter J z can increase QD and entanglement but D z is a more efficient parameter in the antiferromagnetic case.We observe a complex range of QD with the change of D z and a sudden change of QD with the variation of J z in the ferromagnetic case.We show that the decrease durations of both QD and entanglement can be prolonged by increasing DM interaction and reducing noise bandwidth in the evolutionary process.

2D Pauli Equation with Hulthén Potential in the Presence of Aharonov-Bohm Effect

The 2D Pauli equation with Hulthen potential for spin-1/2 particle in the presence of Aharonov-Bohm （AB） field is solved analytically, on the assumption that an effective approximation is used for the centrifugal term. Singular and regular solutions of the problem are obtained. It is shown that the AB field lifts the degeneracy of the energy levels. The range of the flux parameter for which singular solutions are allowed is modified compared to the pure AB case. When the screening parameter vanishes, it is shown that the obtained energy spectrum becomes the same as that of the Aharonov-Bohm Coulomb problem.

Thermal Spin Squeezing as a Signature of Thermal Global Entanglement in Heisenberg Models

We study thermal spin squeezing (TSS) and thermal global entanglement (TGE) in a general Heisenberg spin chain, in the presence of Dzyaloshinskii-Moriya interaction and an external magnetic field. We derive an inequality associating the squeezing parameter and the global concurrence, which establishes (TSS) as a signature of (TGE). The inequality reduces to equality for particular symmetric chains which also associates TSS with bipartite entanglement in such systems. We also check the results by presenting two numerical examples.

Inflation in Non-de Sitter Background with Coherent States

We use the excited coherent states built over the initial non-de Sitter modes,to study the modification of spectra of primordial scalar fluctuation.Non-de Sitter modes are actually the asymptotic solution of the inflaton field equation[J.High Energy Phys.09（2014） 020].We build excited coherent states over the non-de Sitter modes and despite the Jack of interactions in the Lagrangian,we find a non-zero one-point function.It is shown that the primordial non-Gaussianity resulting from excited-de Sitter modes depend both of time and background space-time.It is very tiny of order（≤10^-24）,at the Planck initial fixed time that confirmed by resent observations for single field inflation but it grows in the present epoch.Moreover,our results at the leading order are similar to what obtained with general initial states and in the dS limit leads to standard results[J.Cosmol.Astropart.Phys.1202（2012） 005].We will show that the non-dS modes and its resulting spectrum are more usable for far past time limit.

Quantum Correlation in Three-Qubit Heisenberg Model with Dzyaloshinskii-Moriya Interaction

We investigate the pairwise thermal quantum discord in a three-qubit XXZ model with Dzyaloshinskii-Moriya (DM) interaction. We find that the effects of DM interaction on antiferromagnetic system is distinct from that of ferromagnetic system. The magnetic field supplemented with DM term contribute to enhance the range of quantum discord. It is revealed that the situations where quantum discord fails to indicate a sudden change of groundstate at finite temperature though indicating such a sudden change of groundstate at zero temperature. Dynamics of pairwise thermal quantum discord is considered as well. Thermal quantum discord vanishes in asymptotic limit regardless of its initial values, however, thermal entanglement suddenly disappears in finite time.

Re-examining Photodetachment of H^- near a Spherical Surface using Closed-Orbit Theory

Photodeachment of H^-near a reflective spherical surface was studied by Haneef et al.[J.Phys.B:At.Mol.Opt.Phys.44(2011)195004]using a theoretical imaging method.The total cross section displays interesting oscillations.Here we re-examine the total photodetachment cross section of this system by directly applying the standard closed-orbit theory.Our result for the total cross section differs from the result obtained by Haneef et al.The difference between the two results vanishes in the limit of large radius of the reflective sphere.We argue that the theoretical imaging method developed originally for photodetachment near a Hat surface can not be directly applied to the present system.