Entanglement and quantum phase transition in alternating XY spin chain with next-nearest neighbouring interactions

By using the method of density-matrix renormalization-group to solve the different spin spin correlation functions, the nearest-neighbouring entanglement （NNE） and the next-nearest-neighbouring entanglement （NNNE） of one-dimensional alternating Heisenberg XY spin chain are investigated in the presence of alternating the-nearestneighbouring interaction of exchange couplings, external magnetic fields and the next-nearest neighbouring interaction. For a dimerised ferromagnetic spin chain, the NNNE appears only above a critical dimerized interaction, meanwhile, the dimerized interaction a effects a quantum phase transition point and improves the NNNE to a large extent. We also study the effect of ferromagnetic or antiferromagnetic next-nearest neighbouring （NNN） interaction on the dynamics of NNE and NNNE. The ferromagnetic NNN interaction increases and shrinks the NNE below and above a critical frustrated interaction respectively, while the antiferromagnetic NNN interaction always reduces the NNE. The antiferromagnetic NNN interaction results in a large value of NNNE compared with the case where the NNN interaction is ferromagnetic.

Pure spin polarized transport based on Rashba spin orbit interaction through the Aharonov Bohm interferometer embodied four-quantum-dot ring

The spin-polarized linear conductance spectrum and current–voltage characteristics in a four-quantum-dot ring embodied into Aharonov–Bohm （AB） interferometer are investigated theoretically by considering a local Rashba spin–orbit interaction. It shows that the spin-polarized linear conductance and the corresponding spin polarization are each a function of magnetic flux phase at zero bias voltage with a period of 2π, and that Hubbard U cannot influence the electron transport properties in this case. When adjusting appropriately the structural parameter of inter-dot coupling and dot-lead coupling strength, the electronic spin polarization can reach a maximum value. Furthermore, by adjusting the bias voltages applied to the leads, the spin-up and spin-down currents move in opposite directions and pure spin current exists in the configuration space in appropriate situations. Based on the numerical results, such a model can be applied to the design of a spin filter device.

Symmetry breaking of photonic spin-orbit interactions in metasurfaces

Spin-orbit optical phenomena pertain to the wider class of electromagnetic effects originating from the interaction of the photon spin with the spatial structure and propagation characteristics of an optical wave,mediated by suitable optical media.There are many emerging photonic applications of spin-orbit interactions(SOI)of light,such as control of the optical wave propagation via the spin,enhanced optical manipulation,and generation of structured optical fields.Unfortunately,current applications are based on symmetric SOI,that is,the behaviours of polarized photons with two opposite spins are opposite,leading to the limit of spin-based multiplexers.The symmetry of SOI can be broken in our proposed metasurfaces,consisting of spatially varying birefringence,which can arbitrarily and independently build SOI for two opposite spins without reduction of optical energy usage.We obtain three kinds of dual-functional metasurfaces at visible and infrared wavelengths with high efficiency.Our concept of generation of asymmetric SOI for two spins,using anisotropic metasurfaces,will open new degrees of freedoms for building new types of spin-controlled multifunctional shared-aperture devices for the generation of complex structured optical fields.

Spin-Spin Interactions in Gauge Theory of Gravity, Violation of Weak Equivalence Principle and New Classical Test of General Relativity

很长时间，纺纱纺纱相互作用能仅仅在 Lorentz 对称被计量的一个理论存在，这通常 perturbatively 被相信了，并且有纺纱纺纱相互作用的一个理论不是 renormalizable。但是这不是真的。由在重力的地里学习一个旋转粒子的运动，在那里存在，这被发现在严肃的计量器理论的纺纱纺纱相互作用。它的机制是一个旋转粒子将产生 gravitomagnetic 在时空的地，和这个 gravitomagnetic 领域将与另一个粒子的旋转交往，它将引起纺纱纺纱相互作用。那么，纺纱纺纱相互作用由重力的地被播送。在柱子的纺纱纺纱相互作用的表格牛顿的近似被推出。这结果能也从 Papapetrou 方程被推出。这种相互作用不影响理论的 renormalizability。纺纱纺纱相互作用将违背弱等价原则，并且违背效果是可检测的。一个实验被建议检测弱等价原则的违背的效果。

Dephasing Measurements in InGaAs/AlInAs Heterostructures: Manifestations of Spin-Orbit and Zeeman Interactions

We have measured weak antilocalization effects, universal conductance fluctuations, and Aharonov-Bohm oscillations in the two-dimensional electron gas formed in InGaAs/AlInAs heterostructures. This system possesses strong spin-orbit coupling and a high Landé factor. Phase-coherence lengths of 2 - 4 μm at 1.5 - 4.2 K are extracted from the magnetoconductance measurements. The analysis of the coherence-sensitive data reveals that the temperature dependence of the decoherence rate complies with the dephasing mechanism originating from electron-electron interactions in all three experiments. Distinct beating patterns superimposed on the Aharonov-Bohm oscillations are observed over a wide range of magnetic fields, up to 0.7 Tesla at the relatively high temperature of 1.5 K. The possibility that these beats are due to the interplay between the Aharonov-Bohm phase and the Berry one, different for electrons of opposite spins in the presence of strong spin-orbit and Zeeman interactions in ring geometries, is carefully investigated. It appears that our data are not explained by this mechanism;rather, a few geometrically-different electronic paths within the ring’s width can account for the oscillations’ modulations.

Dynamic magnetic behavior of the mixed spin (2, 5/2) Ising system with antiferromagnetic/antiferromagnetic interactions on a bilayer square lattice

Using the mean-field theory and Glauber-type stochastic dynamics, we study the dynamic magnetic properties of the mixed spin （2, 5/2） Ising system for the antiferromagnetic/antiferromagnetic （AFM/AFM） interactions on the bilayer square lattice under a time varying （sinusoidal） magnetic field. The time dependence of average magnetizations and the thermal variation of the dynamic magnetizations are examined to calculate the dynamic phase diagrams. The dynamic phase diagrams are presented in the reduced temperature and magnetic field amplitude plane and the effects of interlayer coupling interaction on the critical behavior of the system are investigated. We also investigate the influence of the frequency and find that the system displays richer dynamic critical behavior for higher values of frequency than that of the lower values of it. We perform a comparison with the ferromagnetic/ferromagnetic （FM/FM） and AFM/FM interactions in order to see the effects of AFM/AFM interaction and observe that the system displays richer and more interesting dynamic critical behaviors for the AFM/AFM interaction than those for the FM/FM and AFM/FM interactions.

Two Electrons with Spin-Orbit Interactions in InAs Coupled Quantum Dots

我们理论上学习准确 diagonalization 方法与纺纱轨道相互作用(SOI ) 在联合的量点的 InAs 平行(CQD ) 限制的二交往电子的旋转性质。通过汗衫和三位字节混合的导致的纺纱说的 SOI，我们为弱、强壮的 SOI 显示出不同旋转性质。我们在 SOI 下面调查二个电子的协调汗衫三位字节旋转摆动，并且表明取决于 SOI 力量，内部点的分离和外部磁场的旋转摆动的详细行为。为了更好理解旋转动力学的内在的物理，我们为弱、强壮的 SOI 介绍四水平的模型 Hamiltonian，并且发现 SOI 在飞机导致了，有效磁场能是从二电子的刺激精力系列提取的份量上。

Entanglement Entropy Signature of Quantum Phase Transitions in a Multiple Spin Interactions Model

Through the Jordan-Wigner transformation,the entanglement entropy and ground state phase diagrams of exactly solvable spin model with alternating and multiple spin exchange interactions are investigated by means of Green's function theory.In the absence of four-spin interactions,the ground state presents plentiful quantum phases due to the multiple spin interactions and magnetic fields.It is shown that the two-site entanglement entropy is a good indicator of quantum phase transition (QPT).In addition,the alternating interactions can destroy the magnetization plateau and wash out the spin-gap of low-lying excitations.However,in the presence of four-spin interactions,apart from the second order QPTs,the system manifests the first order QPT at the tricritical point and an additional new phase called "spin waves",which is due to the collapse of the continuous tower-like low-lying excitations modulated by the four-spin interactions for large three-spin couplings.

Cooling Torsional Nanomechanical Vibration by Spin-Orbit Interactions

We propose and study a spin-orbit interaction based mechanism to actively cool down the torsional vibrationof a nanomechanical resonator made by semiconductor materials.We show that the spin-orbit interactions of electronscan induce a coherent coupling between the electron spins and the torsional modes of nanomechanical vibration.Thiscoupling leads to an active cooling for the torsional modes through the dynamical thermalization of the resonator by thespin ensemble.

Spin Hall and spin Nernst effects in graphene with intrinsic and Rashba spin-orbit interactions

The spin Hall and spin Nernst effects in graphene are studied based on Green＇s function formalism. We calculate intrinsic contributions to spin Hall and spin Nernst conductivities in the Kane-Mele model with various structures. When both intrinsic and Rashba spin-orbit interactions are present, their interplay leads to some characteristics of the dependence of spin Hall and spin Nernst conductivities on the Fermi level. When the Rashba spin--orbit interaction is smaller than intrinsic spin-orbit coupling, a weak kink in the conductance appears. The kink disappears and a divergence appears when the Rashba spin-orbit interaction enhances. When the Rashba spin-orbit interaction approaches and is stronger than intrinsic spin-orbit coupling, the divergence becomes more obvious.

The conductance and polarization in quantum wires with Rashba and Dresselhaus spin-orbit interactions

The conductance and polarization are studied in one-dimensional ballistic quantum wire with both Rashba and Dresselhaus spin-orbit interactions.Two kinds of structures are considered in the present work,one with mixture of two interactions and the other with sequence structure of them.We find that the conductance and polarization are strongly affected by these two interactions.With both interactions we obtain a multi-peak contour of spin polarization and a dramatic oscillation pattern of spin conductance,which are due to the different combination of the two spin-orbit interactions.

Spin-orbit interaction in coupled quantum wells

We theoretically investigate the spin-orbit interaction in GaAs/AlxGal_xAs coupled quantum wells. We consider the contribution of the interface-related Rashba term as well as the linear and cubic Dresselhaus terms to the spin splitting. For the coupled quantum wells which bear an inherent structure inversion asymmetry, the same probability density distribution of electrons in the two step quantum wells results in a large spin splitting from the interface term. If the widths of the two step quantum wells are different, the electron probability density in the wider step quantum well is considerably higher than that in the narrower one, resulting in the decrease of the spin splitting from the interface term. The results also show that the spin splitting of the coupled quantum well is not significantly larger than that of a step quantum well.

Effects of exchange interaction and spin-fluctuation on the magnetic and magneto-optic properties of NdF_3

The exchange interaction between the electrons in the different magnetic ions and the spin-fluctuation of the magnetic ions exist in the paramagnetic media NdF3. The exchange interaction between the electrons in the different magnetic ions may be equivalent to an effective field Hin that is in direct proportion to the magnetization M. The spin-fluctuation of the magnetic ions leads the coefficient of the effective field to vary with temperature. The effective field is given as Hin = -（0.75 ＋ 0.22T） × 10^-5M in NdF3. When the secondary crystal field effect is taken into account, the magnetic susceptibility and Verdet constant are calculated for NdF3 by means of the effective field Hin and the applied field He. The calculated results are in agreement with the measured ones.

Nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantum-dot ring

We theoretically studied the nonlocal Andreev reflection with Rashba spin-orbital interaction in a triple-quantumdot （QD） ring, which is introduced as Rashba spin-orbital interaction to act locally on one component quantum dot. It is found that the electronic current and spin current are sensitive to the systematic parameters. The interdot spin-flip term does not play a leading role in causing electronic and spin currents. Otherwise the spin precessing terra leads to shift of the peaks of the the spin-up and spin-down electronic currents in different directions and results in the spin current. Moreover, the spin-orbital interaction suppresses the nonlocal Andreev reflection, so we cannot obtain the pure spin current.

Scaling of entanglement entropy for spin chain with Dzyaloshinskii-Moriya interaction

This paper investigates the entanglement in an XX-type spin chain with Dzyaloshinskii--Moriya interaction under an external magnetic field. The von Neumann entropy of entanglement between two blocks for the ground state of the system is evaluated. It analyses and discusses the scaling behaviour of the entanglement entropy.

Thermopower in parallel double quantum dots with Rashba spin-orbit interaction

Based on the Green＇s function technique and the equation of motion approach, this paper theoretically studies the thermoelectric effect in parallel coupled double quantum dots （DQDs）, in which Rashba spin-orbit interaction is taken into account. Rashba spin^rbit interaction contributions, even in a magnetic field, are exhibited obviously in the double quantum dots system for the thermoelectric effect. The periodic oscillation of thermopower can be controlled by tunning the Rashba spin^rbit interaction induced phase. The interesting spin-dependent thermoelectric effects will arise which has important influence on thermoelectric properties of the studied system.

Exact Solution to Spin Squeezing of the Arbitrary-Range Spin Interaction and Transverse Field Model

We investigate spin squeezing effects of trapped ions in an off-resonance optical potential system using the arbitrary range spin spin interaction and transverse field model. The collective spin noises at any time are analyzed exactly. The general expression of spin squeezing factor is presented for arbitrary-range spin interaction. For the nearest-neighbor and next-nearest neighbor spin interaction model, the analytic solutions are reduced from the general expressions. It is shown that the maximum spin squeezing is enhanced for the general arbitrary-range spin interaction compared with the nearest-neighbor interaction model as the long-range interaction with arbitrary sites enforces stronger correlation.

The Pendulum of Dynamic Interactions

In this paper, we present evidence to show that the dynamics of rigid solid bodies is not a closed discipline, particularly in the field of rotational dynamics. From the observation of bodies with intrinsic rotation in our universe, our research group proposes new dynamic hypotheses that explain the behaviour observed when these bodies are subject to new simultaneous non-coaxial rotations. A new gyroscopic conical pendulum was designed for this purpose. Experimental tests initially conducted with this new gyroscopic conical pendulum were repeated for their recording on video, which accompanied this paper for better understanding thereof. These experimental tests positively confirm the new Theory of Dynamic Interactions, and its dynamic laws, which help us to understand the behaviour of this pendulum and, in general, that of the baryonic mass when it is subject to non-coaxial simultaneous rotations. It thus provides a better understanding of the nature and the dynamic behaviour of our universe.

Detection of multi-spin interaction of a quenched XY chain by the average work and the relative entropy

We investigate the nonequilibrium thermodynamics of a quenched XY spin chain with multi-spin interaction in a transverse field.The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters.The influences of the system parameters on the nonequilibrium thermodynamics are investigated.We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics.In addition,our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.