[en] Highlights: • Apply voltages to produce spin-dependent quasiparticle distribution in S/N/F/N/S. • The spin-transition induced by the distribution produces parallel triplet pairs. • Manipulate amplitude and direction of triplet current through changing the voltages. • Superharmonic current will appear when the voltage is applied on one metal region. - Abstract: We study the long-range triplet Josephson current in a clean junction composed of two s-wave superconductors and a normal-metal/ferromagnet/normal-metal trilayer. Through applying the bias voltages on the metal regions by two antiparallel half-metal electrodes, we show that the amplitude and direction of this long-range current can be controlled flexibly. Such current arises from the fact that the applied voltage can produce a nonequilibrium spin-dependent quasiparticle distribution in the metal regions so that the Cooper pairs entering these regions acquire extra momenta, which will lead to a spin-transition process in the metal regions. This process can produce the parallel spin-triplet pairs in the central ferromagnet layer. In particular, if the voltage is applied only to one metal region, we further find that the recently discovered long-range superharmonic Josephson current will appear because of the transport of an even number of parallel spin-triplet pairs

[en] Topological Haldane model recently has been experimentally realized with ultracold atoms. The low energy Hamiltonian in the model can be formally described by the Dirac equation. In this paper, we explore the Zitterbewegung effect of the Dirac quasiparticles in the vicinity of the two nonequivalent Dirac points in the Haldane model. Through analytical and numerical calculation of the evolution of Gaussian wave packets, we find that the Zitterbewegung patterns could be used to characterize the topological phases of the Haldane model. Since the patterns can be detected through standard time-of-flight measurements, our proposal provides a promising scheme to directly visualize the topological phases in ultracold atoms. - Highlights: • The method to probe topological order through wave packet evolution is proposed. • The evolution manifested as Zitterbewegung can be distinguished through the mass terms. • The connection between the topological phases and Zitterbewegung in the Haldane model is found.

[en] Ultracold atoms trapped in optical lattices nowadays have been widely used to mimic various models from condensed-matter physics. Recently, many great experimental progresses have been achieved for producing artificial magnetic field and spin–orbit coupling in cold atomic systems, which turn these systems into a new platform for simulating topological states. In this paper, we give a review focusing on quantum simulation of topologically protected soliton modes and topological insulators in one-dimensional cold atomic system. Firstly, the recent achievements towards quantum simulation of one-dimensional models with topological non-trivial states are reviewed, including the celebrated Jackiw–Rebbi model and Su–Schrieffer–Heeger model. Then, we will introduce a dimensional reduction method for systematically constructing high dimensional topological states in lower dimensional models and review its applications on simulating two-dimensional topological insulators in one-dimensional optical superlattices

[en] The system described by the generalized Birkhoff equations is called a generalized Birkhoffian system. In this paper, the condition under which the generalized Birkhoffian system can be a gradient system is given. The stability of equilibrium of the generalized Birkhoffian system is discussed by using the properties of the gradient system. When there is a parameter in the equations, its influences on the stability and the bifurcation problem of the system are considered. (paper)

[en] The symmetry of Lagrangians of a holonomic variable mass system is studied. Firstly, the differential equations of motion of the system are established. Secondly, the definition and the criterion of the symmetry of the system are presented. Thirdly, the conditions under which there exists a conserved quantity deduced by the symmetry are obtained. The form of the conserved quantity is the same as that of the constant mass Lagrange system. Finally, an example is shown to illustrate the application of the result. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

[en] This paper studies a type of integral and reduction of the generalized Birkhoffian system. An existent condition and the form of the integral are obtained. By using the integral, the dimension of the system can be reduced two degrees. An example is given to illustrate the application of the results. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

[en] This paper proposes a scheme for transferring an N-atom state between two distant cavities via an optical fiber. The scheme is based on adiabatic passage along a dark state. In the scheme, all the atoms are always in ground state, the field mode of the fiber remains in vacuum state, and the field mode of the cavities being excited can be negligible under certain conditions. Therefore, the scheme is very robust against decoherence. The successful probability of implementing the quantum state transfer increases with increasing number of atoms. Furthermore, the interaction time does not need to be accurately adjusted as long as the adiabaticity condition is fulfilled. (general)

[en] We propose a scheme to generate a Greenberger—Horn—Zeilinger (GHZ) state of four atoms trapped in a two-mode optical cavity via an adiabatic passage. The scheme is robust against moderate fluctuations of the experimental parameters. Numerical calculations show that the excited probabilities of both the cavity modes and the atoms are tiny and depend on the pulse peaks of the classical laser fields. For certain decoherence due to the atomic spontaneous emission and the cavity decay, there exits a range of pulse peaks to get a high fidelity. (general)

[en] Artificial pigments of metalloporphyrin derivatives are effective catalysts for the degradation of toxic organic dyes, phenols, and other pollutants. We reported here an interfacial layer-by-layer (LBL) assembly of multiporphyrin arrays on the surface of multi-walled carbon nanotubes (MWNTs) with the use of Na₂PdCl₄ as a connector and manganese (III) meso-tetra(4-pyridyl)porphine acetate (MnTPyP) as a linker, respectively. Thermogravimetric analysis revealed that the relative content of organic species in the MWNT@(Pd-MnTPyP)_n nanocomposites increased gradually with more layers of Pd-MnTPyP assembled. The Soret absorption band of MnTPyP displayed approximately 20-nm redshift in the nanocomposites due to the increase of porphyrin-porphyrin interaction within the Pd-MnTPyP ultrathin films. The specific surface area was about 513.1 and 47.7 m²/g for the original MWNTs and MWNT@(Pd-MnTPyP)₃ nanocomposites, respectively. Finally, the nanocomposites were used as heterogeneous catalysts for catalytic degradation of toxic 1-naphthol, 1,5-dihydroxynaphthalene, 5-amino-1-naphthol, and 1-naphthol-5-sulphonic acid in phosphate buffer, using H₂O₂ as the oxidant. It was revealed that, when the nanocomposites were used, the catalytic efficiency could increase by 2 to 3 orders of magnitude. Higher catalytic efficiency was observed for the naphthols bearing the electron-donating group of hydroxyl or amino than those bearing an electron-withdrawing group of sulfonic acid.

[en] A scheme is proposed for generating a three-dimensional entangled state for two atoms trapped in a cavity by one step via adiabatic passage. In the scheme, the two atoms are always in ground states and the field mode of the cavity excited is negligible under a certain condition. Therefore, the scheme is very robust against decoherence. Furthermore, it needs neither the exact control of all parameters nor the accurate control of the interaction time. It is shown that qutrit entanglement can be generated with a high fidelity. (general)