Ab initio potential energy surface and anharmonic vibration spectrum of NF_(3)^(+)

Potential energy surfaces(PESs), vibrational frequencies, and infrared spectra are calculated for NF_(3)^(+) using ab initio calculations, based on UCCSD(T)/cc-p VTZ combined with vibrational configuration interaction(VCI). Based on an iterative algorithm, the surfaces(SURF) program adds automatic points to the lattice representation of the potential function, the one-dimensional and two-dimensional PESs are calculated after reaching a convergence threshold, finally the smooth image of the potential energy surface is fitted. The PESs accurately account for the interaction between the different modes, with the mode q_(6) symmetrical stretching vibrations having the greatest effect on the potential energy change of the whole system throughout the potential energy surface shift. The anharmonic frequencies are obtained when the VCI matrix is diagonalized. Fundamental frequencies, overtones, and combination bands of NF_(3)^(+) are calculated, which generate the degenerate phenomenon between their frequencies. Finally, the calculated anharmonic frequency is used to plot the infrared spectra.Modal antisymmetric stretching ν_(5) and symmetric stretching ν_(6) exhibit a phenomenon of large-intensity borrowing. This study can provide data to support the characterization in the laboratory.

Effects of twin and stacking faults on the deformation behaviors of Al nanowires under tension loading

The effects of twin spacing and temperature on the deformation behavior of nanotwinned Al under tensile loading are investigated using a molecular dynamic（MD） simulation method.The result shows that the yield strength of nanotwinned Al decreases with the increase of twin spacing,which is related to the repulsive force between twin boundary and the dislocation.The result also shows that there is no strain-hardening at the yield point.On the contrary,the stress is raised by strain hardening in the plastic stage.In addition,we also investigate the effects of stacking fault thickness and temperature on the yield strength of the Al nanowire.The simulation results indicate that the stacking fault may strengthen the Al nanowire when the thickness of the stacking fault is below a critical value.

Efficient scheme for remote preparation of arbitrary n-qubit equatorial states

Recently,a scheme for deterministic remote preparation of arbitrary multi-qubit equatorial states was proposed by Wei et al.[Quantum Inf.Process.1770(2018)].It is worth mentioning that the construction of mutual orthogonal measurement basis plays a key role in quantum remote state preparation.In this paper,a simple and feasible remote preparation of arbitrary n-qubit equatorial states scheme is proposed.In our scheme,the success probability will reach unit.Moreover,there are no coefficient constraint and auxiliary qubits in this scheme.It means that the success probabilities are independent of the coefficients of the entangled channel.The advantage of our scheme is that the mutual orthogonal measurement basis is devised.To accomplish the quantum remote state preparation(RSP)schemes,some new sets of mutually orthogonal measurement basis are introduced.

Teleportation Capability of Six-Qubit Cluster State

Recently Wei-Bo Gao et al.[Phys.Rev.Lett.104 (2010) 020501]; reported on the creation of a 4-photon6-qubit cluster state.It is shown this states can be utilized for perfect teleportation of arbitrary three qubit systemsand controlled teleportation of an arbitrary two-qubit state.Therefore, the six-qubit cluster state as quantum channelsis equivalent to that of maximally six-qubit entangled state.

Effect of twin boundary on nanoimprint process of bicrystal Al thin film studied by molecular dynamics simulation

The effects of a twin boundary（TB） on the mechanical properties of two types of bicrystal Al thin films during the nanoimprint process are investigated by using molecular dynamics simulations.The results indicate that for the TB direction parallel to the imprinting direction,the yield stress reaches the maximum for the initial dislocation nucleation when the mould directly imprints to the TB,and the yield stress first decreases with the increase of the marker interval and then increases.However,for the TB direction perpendicular to the imprinting direction,the effect of the TB location to the imprinting forces is very small,and the yield stress is greater than that with the TB direction parallel to the imprinting direction.The results also demonstrate that the direction of the slip dislocations and the deformation of the thin film caused by spring-back are different due to various positions and directions of the TB.

Theoretical prediction of ion conductivity in solid state HfO_2

A theoretical prediction of ion conductivity for solid state HfO2 is carried out in analogy to ZrO2 based on the density functional calculation. Geometric and electronic structures of pure bulks exhibit similarity for the two materials. Negative formation enthalpy and negative vacancy formation energy are found for YSH （yttria-stabilized hafnia） and YSZ （yttria- stabilized zirconia）, suggesting the stability of both materials. Low activation energies （below 0.7 eV） of diffusion are found in both materials, and YSH＇s is a little higher than that of YSZ. In addition, for both HfO2 and ZrO2, the supercells with native oxygen vacancies are also studied. The so-called defect states are observed in the supercells with neutral and ＋1 charge native vacancy but not in the ＋2 charge one. It can give an explanation to the relatively lower activation energies of yttria-doped oxides and ＋2 charge vacancy supercells. A brief discussion is presented to explain the different YSH ion conductivities in the experiment and obtained by us, and we attribute this to the different ion vibrations at different temperatures.

Effects of tilt interface boundary on mechanical properties of Cu/Ni nanoscale metallic multilayer composites

The effect of tilt interfaces and layer thickness of Cu/Ni multilayer nanowires on the deformation mechanism are investigated by molecular dynamics simulations. The results indicate that the plasticity of the sample with a 45° tilt angle is much better than the others. The yield stress is found to decrease with increasing the tilt angle and it reaches its lowest value at 33°. Then as the tilt angle continues to increase, the yield strength increases. Furthermore, the studies show that with the decrease of layer thickness, the yield strength gradually decreases. The study also reveals that these different deformation behaviors are associated with the glide of dislocation.

Controlled quantum state sharing of arbitrary two-qubit states with five-qubit cluster states

In this paper, we propose a controlled quantum state sharing scheme to share an arbitrary two-qubit state using a five-qubit cluster state and the Bell state measurement. In this scheme, the five-qubit cluster state is shared by a sender （Alice）, a controller （Charlie）, and a receiver （Bob）, and the sender only needs to perform the Bell-state measurements on her particles during the quantum state sharing process, the controller performs a single-qubit projective measurement on his particles, then the receiver can reconstruct the arbitrary two-qubit state by performing some appropriate unitary transformations on his particles after he has known the measured results of the sender and the controller.

Bright-Dark Mode Coupling Model of Plasmons

We propose a coupling model to describe the interaction between the bright and dark modes of the plasmons of a dimer composed of two orthogonal gold nano-rods(GNRs),referred to as the BDMC model.This model shows that the eigen-frequencies of the coupled plasmons are governed by Coulomb potential and electrostatic potential.With the BDMC model,the behaviors of the coupling coefficient and the frequency offset,which is a new parameter introduced here,are revealed.Meanwhile,the asymmetric behavior of two eigen-frequencies related to gap of two GNRs is explained.Using the harmonic oscillator model and the coupled parameters obtained by the BDMC model,the bright mode absorption spectra of the dimer are calculated and the results agree with the numerical simulation.

Theoretical study of spin-forbidden cooling transitions of indium hydride using ab initio methods

The feasibility of spin-forbidden cooling of the In H molecule is investigated based on ab initio quantum chemistry calculations. The potential energy curves for the X^1Σ0^＋^＋, a^3Π0-, a^3Π0^＋, a^3Π1, a-3Π2, A-1Π1, 1-3Σ^0^-＋, and 1-3Σ1-＋states of In H are obtained based on multi-reference configuration interaction plus the Davidson corrections method. The calculated spectroscopic constants are in good agreement with the available experimental data. In addition, the influences of the active space and spin–orbit coupling effects on the potential energy curves and spectroscopic constants are also studied. For Re of a^3Π0^-, a^3Π0^＋, a^3Π1, and a-3Π2 states, the error from large active space is small. The potential energy curve of the A-1Π1state is not smooth for small active space. The spin–orbit coupling effects have great influences on the potential well depth and equilibrium internuclear distance of the A-1Π state. The Franck–Condon factors and radiative lifetimes are obtained on the basis of the transition dipole moments of the a^3Π0^＋）→ X^1Σ0^＋^＋, a-3Π1 → X-1Σ0^＋-＋, and A-1Π1 → X-1Σ0^＋^＋ transitions. Our calculation indicates that the a^3Π1（ ν＇= 0） → X-1Σ0^＋^＋（ν = 0） transition provides a highly diagonally distributed Franck–Condon factor and a short radiative lifetime for the a3Π1 state, which can ensure rapid and efficient laser cooling of In H.The proposed laser drives a-3Π1 → X-1Σ0^＋^＋ transitions by using three wavelengths.

A Relativistic Density Functional Study of the U₂F₆Molecule

All-electronic relativistic density functional theory (DFT) method has been used to study the U2F6 molecule. Results from calculations predict the existence of U2F6 molecule, which has been found to be stable with a multiply bonded U2 unit. The calculations also predict that D3d symmetry of U2F6 is more stable than D3h. The optimized geometries, vibrational frequencies and infrared intensities are reported for D3d symmetry of U2F6 from Becke Three-parameter Lee-Yang-Parr (B3LYP) function with triple zeta valence plus polarization functions basis set (TZP). The bond dissociation energy (BDE) for U-U bond in the U2F6 was obtained using the same method. In addition, the entropies of U2F6 have been investigated at temperature rang from 0 to 3000K in 10 steps using the B3LYP method.

Steered coherence and entanglement in the Heisenberg XX chain under twisted boundary conditions

We study steered coherence(SC)and entanglement in a three-spin Heisenberg XX model under twisted boundary conditions and show that their strengths can be significantly enhanced by tuning the twist angle.The optimal twist angleθ_(opt)for achieving the maximum l_(1) norm of SC isπin the region of weak field B and decreases gradually fromπto 0 when B increases after a critical value,while for the relative entropy of SC,θ_(opt)equalsπin the weak field region and 0 otherwise.The entanglement and the critical temperature above which the entanglement vanishes can also be significantly enhanced by tuning the twist angle from 0 toπ.

Ultrafast Fiber Laser Based on Tungsten Sulphoselenide Materials

Tungsten sulphoselenide(WSSe) alloys, belonging to the transition metal dichalcogenide family, have attracted significant interest in the area of optoelectronics because of their unique optical and electronic properties.However, there has been a dearth of sufficient research on the saturable absorption features and ultrafast lasers applications. Herein, we fabricated a WSSe-microfiber saturable absorber(SA) based on WSSe nanosheets prepared by liquid exfoliation technique. The SA provided a saturation intensity of a modulation depth of 27.95%and a nonsaturable loss of 21.34%. To investigate the potential applications of WSSe in ultrafast photonics, the prepared WSSe-microfiber was incorporated into an Er-doped fiber laser ring cavity. The results demonstrated that the WSSe-based SA successfully generated mode-locking laser pulses with a remarkably short pulse width of 231 fs. Furthermore, the output power of this ultrafast fiber laser reached an impressive value of 15.68 mW.These findings provide valuable views into the unique features of WSSe alloys in the areas of ultrafast optics and develop recipes for SA in ultrafast fiber lasers.

Atomic simulations of influence of twinning on crack propagation of Al

Molecular dynamics simulation was performed to investigate the influence of twin boundary （TB） spacing on crack propaga- tion of AI. This study reveals the orientation of initial crack may affect the mechanism of crack growth obviously. TB strengthens A1 when the crack orientation is parallel with TB because of the hinderance of TB to the emission of the disloca- tions. The results indicate that there is an optimal TB spacing for mechanical properties of the A1, exhibiting reverse HP （Hall-Petch） and HP effect when the TB spacing is near the critical TB spacing. Furthermore, we find that there is a yield strength hardening effect in nanotwinned A1 when the crack orientation is perpendicular to the TB, and the Young＇s modulus is smaller in the nanotwinned A1 than that of twin free A1. The studies also demonstrate that this distinctive deformation behavior is related to nucleation of dislocations and the repulsive force of TB to the dislocations and crack propagation, as well as the distance between the crack tip and the TB.

Testing the nonlocality of entangled states by a new Bell-like inequality

We test a new four-qubit entangled state by the former Bell-like inequalities and find that it violates these inequalities,but not maximally.According to this entangled state,we build a new Bell-like inequality,which is violated by this new state maximally.We also determine the nonlocality of some other four-qubit states by the new inequality.It is found that the new inequality acts as a strong entanglement witness for the new state.This can be used to test new entangled states experimentally.

Critical behavior of the XY spin chain with three-site interaction studied in terms of the Loschmidt echo

The effect of the three-site interaction （α） on the critical behaviors of the XY spin chain is studied in terms of the Loschmidt echo （LE）. The critical lines can be shifted by α, and the anisotropy parameter of the XY chain has no effect on the critical lines. The scaling behaviors of the LE reveal that the dynamical behaviors of the LE are reliable for characterizing quantum phase transition （QPT）.

Optimizing scheme for probabilistic remote preparation of a two-qubit state

Remote state preparation is increasingly becoming attractive in recent years, people have already started theoretical and experimental research, and have made valuable research results. Recently, a scheme for probabilistic remote preparation of a general two-qubit state was proposed （Wang Z Y in Quantum Inf Process. 11：1585, 2012））. In this paper, we present a modified scheme for probabilistic remote preparation of a general two-qubit state. To complete the scheme, the new and feasible complete orthogonal basis vectors have been introduced. Compared with the previous schemes, the advantage of our schemes is that the total success probability of remote state preparation will be greatly improved. The probability of success regarding this scheme is calculated in both general and particular cases. The results show that the success probability of remote state preparation can be improved a little. However, in certain special cases, the success probability of preparation can be greatly improved. In special cases, the success probability of preparation can be improved to 1. The security analysis of the scheme is provided in details.

Effects of Quantum Correction on Dynamical Phase Transition in a Single Species Bosonic Josephson Junction

In this paper, by employing Bogliubov backreaction method, we investigate quantum correction effects on dynamical phase transition in a single species bosonic Josephson junction induced by increasing nonlinear interaction. Compared with mean field theory results, we find that the transition point is shined. The dynamical phase transition is accompanied by a change of the entanglement entropy, which is found to reach a maximum at the transition point of the mean field theory.

Using a quantum dot system to realize perfect state transfer

There are some disadvantages to Nikolopoulos et al.＇s protocol [Nikolopoulos G M, Petrosyan D and Lambropoulos P 2004 Europhys. Left. 65 297] where a quantum dot system is used to realize quantum communication. To overcome these disadvantages, we propose a protocol that uses a quantum dot array to construct a four-qubit spin chain to realize perfect quantum state transfer （PQST）. First, we calculate the interaction relation for PQST in the spin chain. Second, we review the interaction between the quantum dots in the Heitler-London approach. Third, we present a detailed program for designing the proper parameters of a quantum dot array to realize PQST.

Loschmidt Echo of a central spin coupled to an XY spin chain:The role of the Dzyaloshinsky-Moriya interaction

By introducing the Dzyaloshinsky-Moriya （DM） interaction, the Loschmidt Echo （LE） of a quantum sys- tem consisting of a central spin and its surrounding environment characterized by an XY spin chain was investigated analytically and numerically. At the critical points of the magnetic field, the LE presents an obvious decay. The decay amplitude can be tuned by the DM interaction. In some specific intervals the DM interaction can remarkably delay the decay of the LE. On the other hand, the DM interaction can change the effects of the anisotropy parameter on the LE.