Comment on slope of nonlinear FN plot and field enhancement factor

It is common practice to extract field enhancement factor from the slope of FN plot. Many experimentalists working on field electron emission had reported multi-(linear segment) FN plots, which can be divided into several (usually two) linear segments. Then multi-(field enhancement factor) were extracted from the FN plot. They claimed that the field enhancement factor increases with applied field if the FN plot bends downward (vice versus if the FN plot bends upward). We show that this is contrary to fact.Comment: 6 pages, 3 figure

Topological zero-line mode of bilayer graphene with Rashba spin-orbital coupling and staggered sublattice potentials

Domain wall in bilayer graphene with Rashba spin-orbital coupling and staggered sublattice potentials, at the interface between two domains with different gated voltages, is studied. Varying type of zero-line modes are identified, including zero-line mode with pure spin filtering effect. The Y-shape current partition at the junction among three different domains are proposed

Explanation of the Stern-Gerlach splitting of spinor condensates based on symmetry

The Stern-Gerlach splitting of spinor condensates is explained based on the total spin-states with specified SU(2) and permutation symmetries.Comment: 3 pages, 2 figure

Spin-thermodynamics of cold spin-1 atoms decoupled from spatial modes

We study the thermodynamic properties of cold spin-1 atoms with a fixed magnetization M and decoupled from spatial modes. Three temperature domains are found: (0, T1) is a domain of second condensation, namely, both the spatial and spin degrees of freedom are frozen; (T1, T2) is a T - sensitive domain, where the internal energy U \propto T, entropy SE \propto log T, and U/kBT is always less than 3/2; (T2, T3) is the third domain with a maximum entropy. When T is higher than T3, the spatial modes can not be neglected. The appearance of these domains originates from the two gaps: (i) The gap between the ground state and the first excited state, and (ii) the gap between the highest spin-state without spatial excitation and the lowest state with a spatial mode excited. These two gaps are crucial to the low temperature physics and they can be tuned

Analytic study on cold field electron emission from metallic nanowall array

The cold field electron emission from metallic nanowall array is investigated theoretically. Via conformal mapping method, analytic formulas of tunneling barrier, edge field enhancement factor, transmission coefficient, and area emission current density are derived in the semi-classical approximation. The influence of field enhancement effects and screening effects on cold field emission are discussed and the optimal spacing distance between nanowalls for the largest emission current density is found to be a linear function of the height of nanowalls and depends on the applied field.Comment: 14 pages, 7 figure

Effect of magnetic fields on the spin evolution of non-polarized 87Rb Bose-Einstein condensates

The spin mixing dynamics of spin-1 Bose-Einstein condensates with zero magnetization and under an external magnetic field is investigated. The time-dependent solutions are obtained via a diagonalization of the Hamiltonian, which has a simple form under the single mode approximation. The features of evolution are compared in detail with those with the field removed so as to emphasize the effect of the field, which can induce strong oscillation in population of atoms in spin component 0 . A new mode of oscillation characterized by a high frequency and a low frequency, is found when the field is sufficiently strong.Comment: 9 pages, 7 figure

Manifesting pseudo-spin polarization on the edge of graphene via field emission image

We obtain the wave function of field emission from graphene in magnetic field. The emission image reveals structure of the Landau levels and depends on the phase difference between two sub-lattices. The emission pattern is sensitive to the edge potential shift, so a gate voltage can manipulate that.Comment: 10 pages, 4 figure

Hyperfine state entanglement of spinor BEC and scattering atom

Condensate of spin-1 atoms frozen in a unique spatial mode may possess large internal degrees of freedom. The scattering amplitudes of polarized cold atoms scattered by the condensate are obtained with the method of fractional parentage coefficients that treats the spin degrees of freedom rigorously. Channels with scattering cross sections enhanced by square of atom number of the condensate are found. Entanglement between the condensate and the propagating atom can be established by the scattering. The entanglement entropy is analytically obtained for arbitrary initial states. Our results also give hint for the establishment of quantum thermal ensembles in the hyperfine space.Comment: 5 pages, 5 figure

Dark states of dressed spinor Bose-Einstein condensates of spin-1 atoms

Dressed states of spinor Bose-Einstein condensates of spin-1 atoms located in optical cavity of near resonance frequency of excited state of the atom are investigated. The wave function of dark states are given.Comment: 4 page

Interference of the evolutions of Rb and Na Bose-Einstein condensates

Spin evolution of a mixture of two species of spin-1 Bose-Einstein condensates (Rb and Na) has been investigated beyond the mean field theory. Both analytical expression and numerical results on the populations of spin-components are obtained. The interference is found to depend on the initial states and the inter-species interaction sensitively. A number of phenomena arising from the interference have been predicted. In particular, periodic behavior and the alternate appearances of a zone of oscillation and a long quiet zone are found.Comment: 9 pages, 4 figure