Dynamically generated $N^$ resonances from the interaction of two mesons and a baryon

We have studied the ππN system and coupled channels by using of the Faddeev equations and two N＊ and one A states, all of them with jR =1/2＋, have been found in the formalism as dynamically generated states. In addition, signatures for a new N＊ resonance with JR = 1/2＋ are found around an energy of 1920 MeV in the three-body center of mass system.     

Manipulating transition of a two-component Bose–Einstein condensate with a weak δ-shaped laser

We theoretically study the transition dynamics of a two-component Bose–Einstein condensate driven by a train of weak δ-shaped laser pulses. We find that the atomic system can experience peculiar resonant transition even under weak optical excitations and derive the resonance condition by the perturbation method. Employing this mechanism, we propose a scheme to obtain an atomic ensemble with desired odd/even atom number and also a scheme to prepare a nonclassical state of the many-body system with fixed atom number.     

State-to-State Transitions in a Hindmarsh-Rose Neuron System

We investigate the dynamical response of the neuron system to a feeble external signal by using the Hindmarsh-Rose model, when the system is tuned below the first bifurcation point, which corresponds to the period-1 bursting state, and an external signal with a fixed period of about 170s is introduced to the system. It is found that to respond to the outside signal, the system changes from the period-1 state to a period-2 one with variation of the signal amplitude, indicating the occurrence of state-to-state transition （SST）. Moreover, when a signal with different fixed periods is introduced, we can also find a similar transition between other states. Furthermore, the effect of the frequency of the signal on the transition is also discussed. These results may imply that SST plays a constructive role in information processing in neuron systems.     

Exotic vector charmonium and its leptonic decay width

We propose a novel type of interpolating field operator,which manifests the hybrid-like configuration that the charm quark-antiquark pair recoils against gluonic degrees of freedom.A heavy vector charmonium-like state with a mass of 4.33(2) GeV is disentangled from the conventional charmonium states in the quenched approximation.This state has affinity for the hybrid-like operators but couples less to the relevant quark bilinear operator.We also try to extract its leptonic decay constant and give a tentative upper limit that it is less than one tenth of that of J/ψ,which corresponds to a leptonic decay width about dozens of eV.The connection of this state with X(4260) is also discussed.     

Thermal Quantum Discord in Anisotropic Heisenberg XXZ Model with Dzyaloshinskii-Moriya Interaction

The thermal quantum discord （QD） is studied in a two-qubit Heisenberg XXZ system with DzyaloshinskiiMoriya （DM） interaction. We compare the thermal QD with thermal entanglement in this system and find remarkable differences between them. For instance, we show situations where QD decreases asymptotically to zero with temperature T while entanglement decreases to zero at the point of critical temperature, situations where QD decreases with certain tunable parameters such as Dx and Dx when entanglement increases. We find that the characteristic of QD is exotic in this system and this possibly offers a potential solution to enhance entanglement of a system. We also show that tunable parameter Dx is more efficient than parameter Dz in most regions for controlling the QD.     

Energy as Entanglement Witness in Bilinear-Biquadratic Spin-1 Chain

Energy is introduced as an entanglement witness to describe the entanglement property of a quantum system. The thermal equilibrium system is guaranteed to be entangled when system is cooled down below the entanglement temperature TE. By virtue of this concept we exploit the minimum separable state energy and entanglement temperature TE of the bilinear-biquadratic antiferromagnetic spin-1 chain model. We numerically calculate TE for arbitrary values of the strength of biquadratic exchange interaction Q up to N=7. We find TE decreases with Q for fixed N when Q is between -3 and 1/3 （J = 1）. In this regime TE also decreases with N for fixed Q and varies slowly for large N. While the thermal system is always entangled when Q is smaller than -3.     

Sudden birth and sudden death of thermal fidelity in a two-qubit system

We study the energy level crossing and the thermal fidelity in a two-qubit system with the presence of a transverse inhomogeneous magnetic field.With the help of contour plots,we clearly identify the ground states of the system in different regions of parameter space,and discuss the corresponding energy level crossing.The fidelity between the ground state of the system and the state of the system at temperature T is calculated.The result shows that the fidelity is very sensitive to the magnetic field anisotropic factor,indicating that this factor may be used as a controller of the fidelity.The influence of the Yangian transition operators on the fidelity of the system is discussed.We find that the Yangian operators can change the fidelity dramatically and give rise to sudden birth and sudden death phenomena of the thermal fidelity.This makes the corresponding Yangian operators possible candidates for switchers to turn the fidelity on and off.     

Stability of Pairwise Entanglement in Decoherence Environment

Consider the dynamics of a bipartite entangled system in the decoherence environment, we investigate the stability of pairwise entanglement under decoherence.We find that with the same initial entanglement, the lifetime of entanglement in pure states and some mixed states is the longest.We call these special entangled states as Decoherence Path States (DPS).Besides, we present simple analytic evolution equations of the entanglement in these states.The lifetimes can also be obtained easily.Furthermore, we also study the stability of the nearest neighbor entanglement in the ground state of an antiferromagnetic spin-1/2 ring.Coincidentally, the conclusion is that it is as stable as Decoherence Path States.Thus the nearest neighbor entanglement in the ground state is not maximized but it is the most stable.This interesting result links the energy and entanglement in a spin system from a new point of view.     

Logarithmic Quantum Time Crystal

We investigate a time-independent many-boson system, whose ground states are quasi-degenerate and become infinitely degenerate in the thermodynamic limit. Out of these quasi-degenerate ground states we construct a quantum state that evolves in time with a period that is logarithmically proportional to the number of particles,that is, T ～ log N. This boson system in such a state is a quantum time crystal as it approaches the ground state in the thermodynamic limit. The logarithmic dependence of i...     

Constructing a Maximally Entangled Seven-Qubit State via Orthogonal Arrays

Huber et al.[Phys.Rev.Lett.118(2017) 200502] have proved that a seven-qubit state whose three-body marginal states are all maximally mixed does not exist.Here,we propose a method to build a maximally entangled state based on orthogonal arrays to construct maximally entangled seven-qubit states.Using this method,we not only determine that a seven-qubit state whose three-body marginals are all maximally mixed does not exist,but also find the condition for maximally entangled seven-qubit states.We ...     

Study of electronic structures and absorption bands of BaMgF4 crystal with F colour centre

The electronic structures of BaMgF 4 crystals containing an F colour centre are studied within the framework of the fully relativistic self-consistent Direc-Slater theory,using a numerically discrete variational (DV-Xα) method. It is concluded from the calculated results that the energy levels of the F colour centre are located in the forbidden band. The optical transition energy from the ground state to the excited state for the F colour centre is about 5.12 eV,which corresponds to the 242-nm absorption band. These calculated results can explain the origin of the absorption bands.     

Analysis of Y（4660） and Related Bound States with QCD Sum Rules

In this article, we take the vector charmonium-like state Y（4660） as a φ＇ fo（980） bound state （irrespective of the hadro-charmonium and the molecular state） tentatively, and study its mass using the QCD sum rules. The numerical value My = 4.71 ±0.26 GeV is consistent with the experimental data. Considering the SU（3） symmetry of the light flavor quarks and the heavy quark symmetry, we also study the bound states φ＇a（400-1200）, γ′″ fo（980）, and γ′″σ（400-1200） with the QCD sum rules, and make reasonable predictions for their masses.     

Folded Solitary Wave Excitations for （2＋1）-Dimensional Nizhnik-Novikov-Veselov System

With the help of an improved mapping approach and a linear-variable-separation approach, a new family of exact solutions with arbitrary functions of the （2＋1）-dimensional Nizhnik-Novikov-Veselov system （NNV） is derived. Based on the derived solutions and using some multi-valued functions, we find a few new folded solitary wave excitations for the （2＋1）-dimensional NNV system.     

Fabrication and properties of high performance YBa_2Cu_3O_(7-δ) radio frequency SQUIDs with step-edge Josephson junctions

We describe the fabrication of high performance YBa2Cu3O7-δ（YBCO） radio frequency（RF） superconducting quantum interference devices（SQUIDs）, which were prepared on 5 mm×5 mm LaAlO3（LAO） substrates by employing stepedge junctions（SEJs） and in flip-chip configuration with 12 mm×12 mm resonators. The step in the substrate was produced by Ar ion etching with step angles ranging from 47°to 61°, which is steep enough to ensure the formation of grain boundaries（GBs） at the step edges. The YBCO film was deposited using the pulsed laser deposition（PLD） technique with a film thickness half of the height of the substrate step. The inductance of the SQUID washer was designed to be about 157 pH.Under these circumstances, high performance YBCO RF SQUIDs were successfully fabricated with a typical flux-voltage transfer ratio of 83 mV/Φ0, a white flux noise of 29 μΦ0/（Hz）^1/2, and the magnetic field sensitivity as high as 80 fT/（Hz）^1/2.These devices have been applied in magnetocardiography and geological surveys.     

Photoproduction of Mesons off the Deuteron Quasifree and Coherent Processes

Photoproduction of mesons off the deuteron has been investigated at a tagged photon beam of the Bonn ELSA accelerator with the combined Crystal Barrel - TAPS electromagnetic calorimeter for incident photon energies up to 2.5 GeV. The mesons have been detected in coincidence with recoil protons, neutrons and deuterons. This allow the measurement of meson production reactions off the quasifree nucleons bound in the deutron, as well as the coherent production off the deuteron. The comparison of quasifree proton reactions to free proton reactions can confirm or invalidate possible nuclear effects on the extracted cross section reactions. Furthermore the isospin composition of a resonance can be estimated from the comparison of quasifree proton and neutron reactions. The quasifree photoproduction of the η＇ and π°η mesons off nucleons and the coherent photoproduction of π°η--pairs off the deuteron are discussed.     

Exact Solutions to （2＋1）-Dimensional Kaup-Kupershmidt Equation

In this paper, by using the symmetry method, the relationships between new explicit solutions and old ones of the （2＋1）-dimensional Kaup-Kupershmidt （KK） equation are presented. We successfully obtain more general exact travelling wave solutions for （2＋ 1）-dimensional KK equation by the symmetry method and the （G1/G）-expansion method. Consequently, we find some new solutions of （2＋1）-dimensional KK equation, including similarity solutions, solitary wave solutions, and periodic solutions.     

Periodic Wave Solutions for （2＋1）-Dimensional Boussinesq Equation and （3＋ 1）-Dimensional Kadomtsev-Petviashvili Equation

For describing various complex nonlinear phenomena in the realistic world, the higher-dimensional nonlinear evolution equations appear more attractive in many fields of physical and engineering sciences. In this paper, by virtue of the Hirota bilinear method and Riemann theta functions, the periodic wave solutions for the （2＋1）-dimensional Boussinesq equation and （3＋1）-dimensional Kadomtsev Petviashvili （KP） equation are obtained. Furthermore, it is shown that the known soliton solutions for the two equations can be reduced from the periodic wave solutions.     

XYZ particles at Belle

In this paper, I review recent progress in the study of the XYZ particles at Belle. I only focus on studies with charmonium and one or more light mesons in the final states. This covers the X（3872）, X（3915）, Y（4140）, X（4350）, and the charged Z states.     

Darboux Transformations and N-soliton Solutions of Two （2＋1）-Dimensional Nonlinear Equations

Two Darboux transformations of the （2＋1）-dimensional Caudrey-Dodd-Gibbon-Kotera-Sawaka （ CDGKS） equation and （2＋1）-dimensional modified Korteweg-de Vries （mKdV） equation are constructed through the Darboux matrix method, respectively. N-soliton solutions of these two equations are presented by applying the Darboux trans- formations N times. The right-going bright single-soliton solution and interactions of two and three-soliton overtaking collisions of the （2＋1）-dimensional CDGKS equation are studied. By choosing different seed solutions, the right-going bright and left-going dark single-soliton solutions, the interactions of two and three-soliton overtaking collisions, and kink soliton solutions of the （2＋1）-dimensional mKdV equation are investigated. The results can be used to illustrate the interactions of water waves in shallow water.     

Further investigations of the low-lying electronic states of AsO~+ radical

The high level quantum chemistry ab inito multi-reference configuration interaction （MRCI） method with large V5Z basis set is used to calculate the spectroscopic properties of the 15 A-S electronic states （X1∑＋, A I П, 1 △, 1 ∑, 3∑＋, 3П, 3△, 3△ , 5∑＋, 5П, 5△, 1П （II）, ofAsO＋ radical correlated to the dissociation limit As＋（3pg） ＋ O（3pg） and As＋（IDg） ＋ O（1Dg）. In order to obtain better potential curves and more accurate spectroscopic properties, the Davidson modification is taken into account. With the potential energy curves （PECs） determined here, vibrational levels G（v） and inertial rotation constants Bu are computed for all the bound electronic states when the rotational quantum number J equals zero （J = 0）. Except for the states X1∑＋, A1П , it is the first time that the multi-reference configuration calculation has been used on the 13 A-S electronic states of the AsO＋ radical. The potential energy curves of all the A-S electronic states are depicted according to the avoided crossing rule of the same symmetry. Spin-orbit coupling effect （SOC） is introduced into the states X1 ∑＋, A1 П, 3П to consider its effects on the spectroscopic properties. Transition dipole moments （TDMs） from A1П 1, 3 П1 states to the ground state X1∑0＋ are predicted as well.