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Usually the $\ell_2$-norm plays vital roles in quantum physics, acting as the probability of states. In this paper, we show the important roles of $\ell_1$-norm in Yang-Baxter quantum system, in connection with both the braid matrix and quantum entanglements. Concretely, we choose the 2-body and 3-body S-matrices, constrained by Yang-Baxter equation. It has been shown that for 2-body case, the extreme values of $\ell_1$-norm lead to two types of braid matrices and 2-qubit Bell states. Here we show that for the 3-body case, due to the constraint of YBE, the extreme values of $\ell_1$-norm lead to both 3-qubit $|GHZ\rangle$ (local maximum) and $|W\rangle$ (local minimum) states, which cover all 3-qubit genuine entanglements for pure states under SLOCC. This is a more convincing proof for the roles of $\ell_1$-norm in quantum mechanics., Comment: 5 pages, 4 figures + supplementary material

Starting from the Kauffman-Lomonaco braiding matrix transforming the natural basis to Bell states, the spectral parameter describing the entanglement is introduced through Yang-Baxterization. It gives rise to a new type of solutions for Yang-Baxter equation, called the type-II that differs from the familiar solution called type-I of YBE associated with the usual chain models. The Majorana fermionic version of type-II yields the Kitaev Hamiltonian. The introduced $\ell_1$ -norm leads to the maximum of the entanglement by taking the extreme value and shows that it is related to the Wigner's D-function. Based on the Yang-Baxter equation the 3-body S-Matrix for type-II is explicitly given. Different from the type-I solution, the type-II solution of YBE should be considered in describing quantum information. The idea is further extended to $\mathbb{Z}_3$ parafermion model based on $SU(3)$ principal representation. The type-II is in difference from the familiar type-I in many respects. For example, the quantities corresponding to velocity in the chain models obey the Lorentzian additivity $\frac{u+v}{1+uv}$ rather than Galilean rule $(u+v)$. Most possibly, for the type-II solutions of YBE there may not exist RTT relation. Further more, for $\mathbb{Z}_3$ parafermion model we only need the rational Yang-Baxterization, which seems like trigonometric. Similar discussions are also made in terms of generalized Yang-Baxter equation with three spin spaces $\{1,\frac{1}{2},\frac{1}{2}\}$., Comment: 20 pages, 1 figure; Conference paper for Group32 in Prague, 2018. arXiv admin note: text overlap with arXiv:1704.00252 by other authors

The relationships between quantum entangled states and braid matrices have been well studied in recent years. However, most of the results are based on qubits. In this paper, We investigate the applications of 2-qutrit entanglement in the braiding associated with $\mathbb{Z}_3$ parafermion. The 2-qutrit entangled state $|\Psi(\theta)\rangle$, generated by acting the localized unitary solution $\breve{R}(\theta)$ of YBE on 2-qutrit natural basis, achieves its maximal $\ell_1$-norm and maximal von Neumann entropy simultaneously at $\theta=\pi/3$. Meanwhile, at $\theta=\pi/3$, the solutions of YBE reduces braid matrices, which implies the role of $\ell_1$-norm and entropy plays in determining real physical quantities. On the other hand, we give a new realization of 4-anyon topological basis by qutrit entangled states, then the $9\times9$ localized braid representation in 4-qutrit tensor product space $(\mathbb{C}^3)^{\otimes 4}$ are reduced to Jones representation of braiding in the 4-anyon topological basis. Hence, we conclude that the entangled states are powerful tools in analysing the characteristics of braiding and $\breve{R}$-matrix., Comment: 6 pages, 1 figures

We propose a scheme of acoustic spherical cloaking by means of background irrotational flow in compressible fluid. The background flow forms a virtual curved spacetime and guides the sound waves bypass the cloaked objects. To satisfy the laws of real fluid, we show that spatially distributed mass source and momentum source are necessary to supply. The propagation of sound waves in this system is studied via both geometric acoustics approximation and full wave approach. The analytic solution of sound fields is obtained for plane wave incidence. The results reveal the effect of phase retardation (or lead) in comparison with the ordinary transformation-acoustic cloak. In addition, the ability of cloaking is also evaluated for unideal background flows by analyzing the scattering cross section., Comment: 15 pages, 6 figures

Light traveling in time-dependent media has many extraordinary properties which can be utilized to convert frequency, achieve temporal cloaking, and simulate cosmological phenomena. In this paper, we focus on time-dependent axion-type magnetoelectric (ME) media, and prove that light in these media always has two degenerate modes with opposite circular polarizations corresponding to one wave vector $\mathbf{k}$, and name this effect "time circular birefringence" (TCB). By interchanging the status of space and time, the pair of TCB modes can appear simultaneously via "time refraction" and "time reflection" of a linear polarized incident wave at a time interface of ME media. The superposition of the two TCB modes causes the "time Faraday effect", namely the globally unified polarization axes rotate with time. A circularly polarized Gaussian pulse traversing a time interface is also studied. If the wave-vector spectrum of a pulse mainly concentrates in the non-traveling-wave band, the pulse will be trapped with nearly fixed center while its intensity will grow rapidly. In addition, we propose an experimental scheme of using molecular fluid with external time-varying electric and magnetic fields both parallel to the direction of light to realize these phenomena in practice., Comment: 17 pages, 6 figures

We construct the 1D $\mathbb{Z}_3$ parafermionic model based on the solution of Yang-Baxter equation and express the model by three types of fermions. It is shown that the $\mathbb{Z}_3$ parafermionic chain possesses both triple degenerate ground states and non-trivial topological winding number. Hence, the $\mathbb{Z}_3$ parafermionic model is a direct generalization of 1D $\mathbb{Z}_2$ Kitaev model. Both the $\mathbb{Z}_2$ and $\mathbb{Z}_3$ model can be obtained from Yang-Baxter equation. On the other hand, to show the algebra of parafermionic tripling intuitively, we define a new 3-body Hamiltonian $\hat{H}_{123}$ based on Yang-Baxter equation. Different from the Majorana doubling, the $\hat{H}_{123}$ holds triple degeneracy at each of energy levels. The triple degeneracy is protected by two symmetry operators of the system, $\omega$-parity $P$($\omega=e^{{\textrm{i}\frac{2\pi}{3}}}$) and emergent parafermionic operator $\Gamma$, which are the generalizations of parity $P_{M}$ and emergent Majorana operator in Lee-Wilczek model, respectively. Both the $\mathbb{Z}_3$ parafermionic model and $\hat{H}_{123}$ can be viewed as SU(3) models in color space. In comparison with the Majorana models for SU(2), it turns out that the SU(3) models are truly the generalization of Majorana models resultant from Yang-Baxter equation., Comment: Main text: 12 pages; Supplementary: 4 pages

Donoho and Stark have shown that a precise deterministic recovery of missing information contained in a time interval shorter than the time-frequency uncertainty limit is possible. We analyze this signal recovery mechanism from a physics point of view and show that the well-known Shannon-Nyquist sampling theorem, which is fundamental in signal processing, also uses essentially the same mechanism. The uncertainty relation in the context of information theory, which is based on Fourier analysis, provides a criterion to distinguish Shannon-Nyquist sampling from compressed sensing. A new signal recovery formula, which is analogous to Donoho-Stark formula, is given using the idea of Shannon-Nyquist sampling; in this formulation, the smearing of information below the uncertainty limit as well as the recovery of information with specified bandwidth take place. We also discuss the recovery of states from the domain below the uncertainty limit of coordinate and momentum in quantum mechanics and show that in principle the state recovery works by assuming ideal measurement procedures. The recovery of the lost information in the sub-uncertainty domain means that the loss of information in such a small domain is not fatal, which is in accord with our common understanding of the uncertainty principle, although its precise recovery is something we are not used to in quantum mechanics. The uncertainty principle provides a universal sampling criterion covering both the classical Shannon-Nyquist sampling theorem and the quantum mechanical measurement., Comment: 27 pages. Journal of Physical Society of Japan (in press)

A new realization of doubling degeneracy based on emergent Majorana operator $\Gamma$ presented by Lee-Wilczek has been made. The Hamiltonian can be obtained through the new type of solution of Yang-Baxter equation, i.e. $\breve{R}(\theta)$-matrix. For 2-body interaction, $\breve{R}(\theta)$ gives the "superconducting" chain that is the same as 1D Kitaev chain model. The 3-body Hamiltonian commuting with $\Gamma$ is derived by 3-body $\breve{R}_{123}$-matrix, we thus show that the essence of the doubling degeneracy is due to $[\breve{R}(\theta), \Gamma]=0$. We also show that the extended $\Gamma'$-operator is an invariant of braid group $B_N$ for odd $N$. Moreover, with the extended $\Gamma'$-operator, we construct the high dimensional matrix representation of solution to Yang-Baxter equation and find its application in constructing $2N$-qubit Greenberger-Horne-Zeilinger state for odd $N$., Comment: 12 pages, 1 figures

This paper investigates the physical effects of Yang-Baxter equation (YBE) to quantum entanglements through the 3-body S-matrix in entangling parameter space. The explicit form of 3-body S-matrix $\breve{R}_{123}(\theta,\varphi)$ based on the 2-body S-matrices is given due to the factorization condition of YBE. The corresponding chain Hamiltonian has been obtained and diagonalized, also the Berry phase for 3-body system is given. It turns out that by choosing different spectral parameters the $\breve{R}(\theta,\varphi)$-matrix gives GHZ and W state respectively. The extended 1-D Kitaev toy model has been derived. Examples of the role of the model in entanglement transfer are discussed., Comment: 13 pages, 2 figures

We prove that the action of the Yangian algebra Y(sl_N) is better described by the principal generators on the tensor product of the fundamental representation and its dual. The generalized Bell states or maximally entangled states are permuted by the principal generators in a dramatically simple manner on the tensor product. Under the Yangian symmetry the new quantum number J^2 is also explicitly computed, which gives an explanation for these maximally entangled states., Comment: 15 pages

The topological basis associated with Birman-Wenzl-Murakami algebra (BWMA) is constructed and the three dimensional forms of braiding matrices S have been found for both $S^+=S$ and $S^+=S^{-1}$. A familiar spin-1 model related to braiding matrix associated with BWMA is discussed. The extreme points $(\theta=\pm\pi/2$ and $\pm\pi)$ of L1-norm and von Neumann entropy are shown to be connected to each other. Through the general discussion and examples we then point out that the L1-norm describes quantum entanglement., Comment: 38 pages, 11 figures

An imaging system based on single photon counting and compressive sensing (ISSPCCS) is developed to reconstruct a sparse image in absolute darkness. The single photon avalanche detector and spatial light modulator (SLM) of aluminum micro-mirrors are employed in the imaging system while the convex optimization is used in the reconstruction algorithm. The image of an object in the very dark light can be reconstructed from an under-sampling data set, but with very high SNR and robustness. Compared with the traditional single-pixel camera used a photomultiplier tube (PMT) as the detector, the ISSPCCS realizes photon counting imaging, and the count of photons not only carries fluctuations of light intensity, but also is more intuitive.

In this paper, we review the methodology of transformation optics, which can construct invisibility cloak through the transformation of coordinates based on the form invariance of Maxwell's equations. Three different ways to define the components of electromagnetic fields are compared for removing some ambiguities. The analytical expressions of light-ray and wave-normal ray are derived in spherical and cylindrical ideal invisibility cloaks created with any continuous radial transformation functions, and their physical interpretation is also given. Using the duality principle in anisotropic media, we prove that light-ray vector satisfies "ray-vector eikonal equation" corresponding to the usual "wave-vector eikonal equation". The results interpret why the wave vector maps to the ray vector transferring from the virtual space to the physical space, but not the wave vector. As an application, we investigate the special transformation functions which make the light-ray function satisfy harmonic equation., Comment: 31 pages, 5 figures

A new reconstruction method for Wigner function is reported for quantum tomography based on compressed sensing. By analogy with computed tomography, Wigner functions for some quantum states can be reconstructed with less measurements utilizing this compressed sensing based method.

The effect of electrostatic shielding for a spherical invisibility cloak with arbitrary charges inside is investigated. Our result reveals that the charge inside the cloak is a crucial factor to determine the detection. When charged bodies are placed inside the cloak with an arbitrary distribution, the electric fields outside are purely determined by the total charges just as the fields of a point charge at the center of the cloak. As the total charges reduce to zero, the bodies can not be detected. On the other hand, if the total charges are nonzero, the electrostatic potential inside an ideal cloak tends to infinity. For unideal cloaks, this embarrassment is overcome, while they still have good behaviors of shielding. In addition, the potential across the inner surface of an ideal cloak is discontinuous due to the infinite polarization of the dielectric, however it can be alternatively interpreted as the dual Meissner effect of a dual superconductive layer with a surface magnetic current., Comment: 7 pages, 8 figures

~Based on the gauge invariant quark canonical momentum we construct two theoretically possible decompositions of nucleon momentum to those of quarks and gluons. We predict that either 6% or 21% of nucleon momentum is carried by gluons, depending on what type of gluons are in nucleons. We clarify the existing confusions on this problem and discuss the physical implications of our result on the proton spin crisis problem.

We discuss the shortfalls of existing resolutions of the long-standing gauge invariance problem of the canonical decomposition of the nucleon spin to the spin and angular momentum of quarks and gluons. We provide two logically flawless expressions of nucleon spin which have different physical meanings, using the gauge independent Abelian decomposition. The first one is based on the assumption that all gluons (binding and valence gluons) contribute to the nucleon spin, but the second one is based on the assumption that only the binding gluons (and the quarks) contribute to it. We propose the second expression to be the physically correct one.

The role of $\ell_{1}$-norm in Quantum Mechanics (QM) has been studied through Wigner's D-functions where $\ell_{1}$-norm means $\sum_{i}\left|C_{i}\right|$ for $\left|\Psi\right\rangle =\sum_{i}C_{i}\left|\psi_{i}\right\rangle $ if $\left|\psi_{i}\right\rangle $ are uni-orthogonal and normalized basis. It was shown that the present two types of transformation matrix acting on the natural basis in physics consist in an unified braiding matrix, which can be viewed as a particular solution of the Yang-Baxter equation (YBE). The maximum of the $\ell_{1}$-norm is connected with the maximally entangled states and topological quantum field theory (TQFT) with two-component anyons while the minimum leads to the permutation for fermions or bosons., Comment: 17 pages, 5 figures

The symmetry operator $Q=Y^2$ is introduced to re-describe the Heisenberg spin triangles in the \{V6\} molecule, where $\mathbf{Y}$ stands for the Yangian operator which can be viewed as special form of Dzyaloshiky-Moriya (DM) interaction for spin 1/2 systems. Suppose a parallelogram Heisenberg model that is comprised of four 1/2-spins commutes with $Q$, which means that it possesses Yangian symmetry, we show that the ground state of the Hamiltonian $H_4$ for the model allows to take the total spin S=1 by choosing some suitable exchange constants in $H_4$. In analogy to the molecular \{V6\} where the two triangles interact through Yangian operator we then give the magnetization for the theoretical molecule "\{V8\}" model which is comprised of two parallelograms. Following the example of molecule \{V15\}, we give another theoretical molecule model regarding the four 1/2-spins system with total spin S=1 and predict the local moments to be 1/10u_B, 9/10u_B, 1/10u_B,9/10u_B respectively., Comment: 24 pages,8 figures, submitted to Annals of Physics

The canonical equations of the optical cloaking proposed by Shurig, Pendry and Smith has been proved to be equivalent to the geodesic in a 3-dimensional curved space. Carrying out the argument we extend to the 4-dimensional Riemannian space where the extra time item appears as the potential term in the canonical equations. The physical meaning of the results is interpreted., Comment: 15 pages, 6 figures

Motivated to simplify the structure of tensor representations we give a new set of generators for the Yangian $Y(sl(n))$ using the principal realization in simple Lie algebras. The isomorphism between our new basis and the standard Cartan-Weyl basis is also given. We show by example that the principal basis simplifies the Yangian action significantly in the tensor product of the fundamental representation and its dual., Comment: 10 pages

We show that all pure entangled states of two $d$-dimensional quantum systems (i.e., two qudits) can be generated from an initial separable state via a universal Yang--Baxter matrix if one is assisted by local unitary transformations., Comment: 4 pages, 2 figures

Entanglement is believed to be crucial in macroscopic physical systems for understanding the collective quantum phenomena such as quantum phase transitions. We start from and solve exactly a novel Yang-Baxter spin-1/2 chain model with inhomogeneous and anisotropic short-range interactions. For the ground state, we show the behavior of neighboring entanglement in the parameter space and find that the inhomogeneous coupling strengths affect entanglement in a distinctive way from the homogeneous case, but this would not affect the coincidence between entanglement and quantum criticality., Comment: 7 pages, 3 figures

Spin interaction Hamiltonians are obtained from the unitary Yang--Baxter $\breve{R}$-matrix. Based on which, we study Berry phase and quantum criticality in the Yang--Baxter systems., Comment: 7 pages, no figures. Accepted for publication in Annals of Physics

In this paper, several proposals of optically simulating Yang-Baxter equations have been presented. Motivated by the recent development of anyon theory, we apply Temperley-Lieb algebra as a bridge to recast four-dimentional Yang-Baxter equation into its two-dimensional counterpart. In accordance with both representations, we find the corresponding linear-optical simulations, based on the highly efficient optical elements. Both the freedom degrees of photon polarization and location are utilized as the qubit basis, in which the unitary Yang-Baxter matrices are decomposed into combination of actions of basic optical elements., Comment: 15 pages, 7 figures; introduction and second section are dramatically rewritten, in order to improve the physical sense

In this paper we discuss a new type of 4-dimensional representation of the braid group. The matrices of braid operations are constructed by q-deformation of Hamiltonians. One is the Dirac Hamiltonian for free electron with mass m, the other, which we find, is related to the Bogoliubov Hamiltonian for quasiparticles in $^3$He-B with the same free energy and mass being m/2. In the process, we choose the free q-deformation parameter as a special value in order to be consistent with the anyon description for fractional quantum Hall effect with $\nu = 1/2$., Comment: 3 pages, 5 figures

In this paper we describe connections among extraspecial 2-groups, unitary representations of the braid group and multi-qubit braiding quantum gates. We first construct new representations of extraspecial 2-groups. Extending the latter by the symmetric group, we construct new unitary braid representations, which are solutions to generalized Yang-Baxter equations and use them to realize new braiding quantum gates. These gates generate the GHZ (Greenberger-Horne-Zeilinger) states, for an arbitrary (particularly an \emph{odd}) number of qubits, from the product basis. We also discuss the Yang-Baxterization of the new braid group representations, which describes unitary evolution of the GHZ states. Our study suggests that through their connection with braiding gates, extraspecial 2-groups and the GHZ states may play an important role in quantum error correction and topological quantum computing., Comment: v1: Latex, 28 pages; v2: comment and references added; v3: Title and authors changed. Significantly more concise than previous versions, now 21 pages

We show that braiding transformation is a natural approach to describe quantum entanglement, by using the unitary braiding operators to realize entanglement swapping and generate the GHZ states as well as the linear cluster states. A Hamiltonian is constructed from the unitary $\check{R}_{i,i+1}(\theta,\phi)$-matrix, where $\phi=\omega t$ is time-dependent while $\theta$ is time-independent. This in turn allows us to investigate the Berry phase in the entanglement space., Comment: 6 pages, 2 figures. Published version

Recent study suggests that there are natural connections between quantum information theory and the Yang--Baxter equation. In this paper, in terms of the generalized almost-complex structure and with the help of its algebra, we define the generalized Bell matrix to yield all the GHZ states from the product base, prove it to form a unitary braid representation and present a new type of solution of the quantum Yang--Baxter equation. We also study Yang-Baxterization, Hamiltonian, projectors, diagonalization, noncommutative geometry, quantum algebra and FRT dual algebra associated with this generalized Bell matrix., Comment: 17 pages, latex

The virtual knot theory is a new interesting subject in the recent study of low dimensional topology. In this paper, we explore the algebraic structure underlying the virtual braid group and call it the virtual Temperley--Lieb algebra which is an extension of the Temperley--Lieb algebra by adding the group algebra of the symmetrical group. We make a connection clear between the Brauer algebra and virtual Temperley--Lieb algebra, and show the algebra generated by permutation and its partial transpose to be an example for the virtual Temperley--Lieb algebra and its important quotients., Comment: 10 pages, latex

The antisymmetric solution of the braided Yang--Baxter equation called the Bell matrix becomes interesting in quantum information theory because it can generate all Bell states from product states. In this paper, we study the quantum algebra through the FRT construction of the Bell matrix. In its four dimensional representations via the coproduct of its two dimensional representations, we find algebraic structures including a composition series and a direct sum of its two dimensional representations to characterize this quantum algebra. We also present the quantum algebra using the FRT construction of Yang--Baxterization of the Bell matrix., Comment: v1: 15 pages, 2 figures, latex; v2: 18 pages, 2 figures, latex, references and notes added

A cuprate superconductor model based on the analogy with atomic nuclei was shown by Iachello to have an $su(3)$ structure. The mean-field approximation Hamiltonian can be written as a linear function of the generators of $su(3)$ algebra. Using algebraic method, we derive the eigenvalues of the reduced Hamiltonian beyond the subalgebras $u(1)\bigotimes u(2)$ and $so(3)$ of $su(3)$ algebra. In particular, by considering the coherence between s- and d-wave pairs as perturbation, the effects of coherent term upon the energy spectrum are investigated.

In this paper, the Yangian relations are tremendously simplified for Yangians associated to SU(2), SU(3), SO(5) and SO(6) based on RTT relations that much benefit the realization of Yangian in physics. The physical meaning and some applications of Yangian have been shown., Comment: 33pages, 1 figure

The effect of inhomogeneous coupling between three-level atoms and external light fields is studied in the electromagnetically induced transparency (EIT) quantum memory techqnique. By introducing a subensemble-atomic system to deal with present inhomogeneous coupling case, we find there is a non-symmetric dark-state subspace (DSS) that allows the EIT quantum memory technique to function perfectly. This shows that such memory scheme can work ideally even if the atomic state is very far from being a symmetric one., Comment: 7 pages

We propose a scheme to generate quantum spin current via optical dipole transition process. By coupling a three-level system based on the spin states of charged particles (electrons or holes in semiconductor) to the angular momentum states of the radiation, we show that a pure quantum spin current can be generated. No spin-orbit interaction is needed in this scheme. We also calculate the effect of nonmagnetic impurities on the created spin currents and show that the vertex correction of the spin hall conductivity in the ladder approximation is exactly zero., Comment: 5 pages, 3 figures

We investigate the maximal violation of Bell inequalities for two $d$-dimensional systems by using the method of Bell operator. The maximal violation corresponds to the maximal eigenvalue of the Bell operator matrix. The eigenvectors corresponding to these eigenvalues are described by asymmetric entangled states. We estimate the maximum value of the eigenvalue for large dimension. A family of elegant entangled states $|\Psi>_{\rm app}$ that violate Bell inequality more strongly than the maximally entangled state but are somewhat close to these eigenvectors is presented. These approximate states can potentially be useful for quantum cryptography as well as many other important fields of quantum information., Comment: 6 pages, 1 figure. Revised version

Entanglement of remote atom lasers is obtained via quantum state transfer technique from lights to matter waves in a five-level $M$-type system. The considered atom-atom collisions can yield an effective Kerr susceptibility for this system and lead to the self- and cross- phase modulation between the two output atom lasers. This effect results in generation of entangled states of output fields. Particularly, under different conditions of space-dependent control fields, the entanglement of atom lasers and of atom-light fields can be obtained, respectively. Furthermore, based on the Bell-state measurement, an useful scheme is proposed to spatially separate the generated entangled atom lasers., Comment: 8 pages, 3 figure

The unitary braiding operators describing topological entanglements can be viewed as universal quantum gates for quantum computation. With the help of the Brylinskis's theorem, the unitary solutions of the quantum Yang--Baxter equation can be also related to universal quantum gates. This paper derives the unitary solutions of the quantum Yang--Baxter equation via Yang--Baxterization from the solutions of the braided relation. We study Yang--Baxterizations of the non-standard and standard representations of the six-vertex model and the complete solutions of the non-vanishing eight-vertex model. We construct Hamiltonians responsible for the time-evolution of the unitary braiding operators which lead to the Schr{\"o}dinger equations., Comment: v1:36 pages, 3 figures, latex; v2: 35 pages, typo errors corrected and diagrams redrawn; v3: RevTex4, 24 pages, 3 .eps files; v4: latex, references updated

It is fundamental to view unitary braiding operators describing topological entanglements as universal quantum gates for quantum computation. This paper derives a unitary solution of the Quantum Yang--Baxter equation via Yang--Baxterization and constructs the Hamiltonian responsible for the time-evolution of the unitary braiding operator., Comment: v1, 11 pages; v2, 11 pages; v3, 12 pages, additional comments; v4, 10 pages; v5, published version

A model for the coexistence of p-wave superconductivity (SC) and ferroelectricity (FE) is presented. The Hamiltonian of SC sector and FE sector can be diagonalized by using the $so(5)$ and $h(4)$ algebraic coherent states respectively. We assume a minimal symmetry-allow coupling and simplify the total Hamiltonian through a double mean-field approximation (DMFA). A variational coherent-state (VCS) trial wave-function is applied for the ground state. It is found that the ferroelectricity gives rise to the magnetic field effect of p-wave superconductivity., Comment: 11pages,no figure

The dynamics of the domain wall (DW) in a biaxial ferromagnet interacting with a spin-polarized current are described by sine-gordon (SG) equation coupled with Gilbert damping term in this paper. Within our frame-work of this model, we obtain a threshold of the current in the motion of a single DW with the perturbation theory on kink soliton solution to the corresponding ferromagnetic system, and the threshold is shown to be dependent on the Gilbert damping term. Also, the motion properties of the DW are discussed for the zero- and nonzero-damping cases, which shows that our theory to describe the dynamics of the DW are self-consistent., Comment: 7pages, 3figures

We study in detail the interesting dynamical symmetry and its applications in various atomic systems with electromagnetically induced transparency (EIT) in this paper. By discovering the symmetrical Lie group of various atomic systems, such as single-atomic-ensemble composed of complex $m$-level $(m>3)$ atoms, and $two$-atomic-ensemble and even multi-atomic-ensemble system composed of of $three$-level atoms etc., one can obtain the general definition of dark-state polaritons (DSPs), and then the dark-states of these different systems. The symmetrical properties of the multi-level system and multi-atomic-ensemble system are shown to be dependent on some characteristic parameters of the EIT system. Furthermore, a controllable scheme to generate quantum entanglement between lights or atoms via quantized DSPs theory is discussed and the robustness of this scheme is analyzed by confirming the validity of adiabatic passage conditions in this paper., Comment: 14pages, 2figures, Phys. Lett. A, In print

Two-flavor atom laser in a vortex state is obtained and analyzed via electromagnetically induced transparency (EIT) technique in a five-level $M$ type system by using two probe lights with $\pm z$-directional orbital angular momentum $\pm l\hbar$, respectively. Together with the original transfer technique of quantum states from light to matter waves, the present result can be extended to generate continuous two-flavor vortex atom laser with non-classical atoms., Comment: 5 pages, 1 figure; The previous version (v2) is a wrong one; this is the published version

We propose a scheme to obtain soliton atom laser with nonclassical atoms based on quantum state transfer process from light to matter waves in nonlinear case, which may find novel applications in, e.g., an atom interferometer. The dynamics of the atomic gray solitons and the accompanied frequency chirp effect are discussed., Comment: 6 pages, 3 figures

We examine in detail the quantum memory technique for photons in a double $\Lambda$ atomic ensemble in this work. The novel application of the present technique to create two different quantum probe fields as well as entangled states of them is proposed. A larger zero-degeneracy class besides dark-state subspace is investigated and the adiabatic condition is confirmed in the present model. We extend the single-mode quantum memory technique to the case with multi-mode probe fields, and reveal the exact pulse matching phenomenon between two quantized pulses in the present system., Comment: 7 pages, 1 figure, to appear in Euro. Phys. J. D

We show the possible stable soliton generation for the dark-state polaritons (DSPs) in an electromagnetic induced transparency (EIT) medium composed of $\Lambda$-type atoms. Whether the solitons are dark or bright can be controlled by the coupling field intensity and the one photon detuning of the probe field. Besides, the velocity and time width of the solitons also can be adjusted by the coupling light., Comment: 6 pages, 1 figure. Phys. Rev. A, to be published

The transfer technique of quantum states from light to collective atomic excitations in a double $\Lambda$ type system is extended to matter waves in this paper, as a novel scheme towards making a continuous atom laser. The intensity of the output matter waves is found to be determined by the initial relative phase of the two independent coherent probe lights, which may indicate an interesting method for the measurement of initial relative phase of two independent light sources., Comment: 5 pages, 2 figures

We proposed a scheme to realize a controlled-NOT quantum logic gate in a dimer of exchange coupled single-molecule magnets, $[\textrm{Mn}_4]_2$. We chosen the ground state and the three low-lying excited states of a dimer in a finite longitudinal magnetic field as the quantum computing bases and introduced a pulsed transverse magnetic field with a special frequency. The pulsed transverse magnetic field induces the transitions between the quantum computing bases so as to realize a controlled-NOT quantum logic gate. The transition rates between the quantum computing bases and between the quantum computing bases and other excited states are evaluated and analyzed., Comment: 7 pages, 2 figures

The superfluid-Mott insulator transition of spin-2 boson atoms with repulsive interaction in an optical lattice in a magnetic field is presented. By using the mean field theory, Mott ground states and phase diagrams of superfluid-Mott insulator transition at zero temperature are revealed. Applied magnetic field leads to some phase boundaries splitting. For all the initial Mott ground states containing multiple spin components, different spin components take on different phase boundaries. It is found that in this system the phase boundaries with different magnetization can be moved in different ways by only changing the intensity of the applied magnetic field., Comment: 18 pages, 6 figures. submitted to Phys. Rev. A