Field-induced confinement in (TMTSF)2ClO4 under accurately aligned magnetic fields

We present transport measurements along the least conducting c direction of the organic superconductor (TMTSF)2ClO4, performed under an accurately aligned magnetic field in the low temperature regime. The experimental results reveal a two-dimensional confinement of the carriers in the (a,b) planes which is governed by the magnetic field component along the b' direction. This 2-D confinement is accompanied by a metal-insulator transition for the c axis resistivity. These data are supported by a quantum mechanical calculation of the transverse transport taking into account in self consistent treatment the effect of the field on the interplane Green function and on the intraplane scattering time

Simple scheme for expanding a polarization-entangled W state by adding one photon

We propose a simple scheme for expanding a polarization-entangled W state. By mixing a single photon and one of the photons in an n-photon W state at a polarization-dependent beam splitter (PDBS), we can obtain an (n+1)-photon W state after post-selection. Our scheme also opens the door for generating n-photon W states using single photons and linear optics.Comment: 3 pages, 2 figure

Reducing Residual-Mass Effects for Domain-Wall Fermions

It has been suggested to project out a number of low-lying eigenvalues of the four-dimensional Wilson--Dirac operator that generates the transfer matrix of domain-wall fermions in order to improve simulations with domain-wall fermions. We investigate how this projection method reduces the residual chiral symmetry-breaking effects for a finite extent of the extra dimension. We use the standard Wilson as well as the renormalization--group--improved gauge action. In both cases we find a substantially reduced residual mass when the projection method is employed. In addition, the large fluctuations in this quantity disappear.Comment: 18 pages, 10 figures, references updated, comments adde

Tunneling anisotropic magnetoresistance in multilayer-(Co/Pt)/AlOx/Pt structures

We report observations of tunneling anisotropic magnetoresitance (TAMR) in vertical tunnel devices with a ferromagnetic multilayer-(Co/Pt) electrode and a non-magnetic Pt counter-electrode separated by an AlOx barrier. In stacks with the ferromagnetic electrode terminated by a Co film the TAMR magnitude saturates at 0.15% beyond which it shows only weak dependence on the magnetic field strength, bias voltage, and temperature. For ferromagnetic electrodes terminated by two monolayers of Pt we observe order(s) of magnitude enhancement of the TAMR and a strong dependence on field, temperature and bias. Discussion of experiments is based on relativistic ab initio calculations of magnetization orientation dependent densities of states of Co and Co/Pt model systems.Comment: 4 pages, 5 figures, to be published in Phys. Rev. Let

Generation of Three-Qubit Entangled W-State by Nonlinear Optical State Truncation

We propose an alternative scheme to generate W state via optical state truncation using quantum scissors. In particular, these states may be generated through three-mode optical state truncation in a Kerr nonlinear coupler. The more general three-qubit state may be also produced if the system is driven by external classical fields.Comment: 7 pages, 2 figur

Quantum teleportation via a W state

We investigate two schemes of the quantum teleportation with a $W$ state, which belongs to a different class from a Greenberger-Horne-Zeilinger class. In the first scheme, the $W$ state is shared by three parties one of whom, called a sender, performs a Bell measurement. It is shown that quantum information of an unknown state is split between two parties and recovered with a certain probability. In the second scheme, a sender takes two particles of the $W$ state and performs positive operator valued measurements in two ways. For two schemes, we calculate the success probability and the average fidelity. We show that the average fidelity of the second scheme cannot exceed that of the first one.Comment: 7 pages, 1 figur

Limits on Interactions between Weakly Interacting Massive Particles and Nucleons Obtained with NaI(Tl) crystal Detectors

Limits on the cross section for weakly interacting massive particles (WIMPs) scattering off nucleons in the NaI(Tl) detectors at the Yangyang Underground Laboratory are obtained with a 2967.4 kg*day data exposure. Nuclei recoiling are identified by the pulse shape of scintillating photon signals. Data are consistent with no nuclear recoil hypothesis, and 90% confidence level upper limits are set. These limits partially exclude the DAMA/LIBRA region of WIMP-sodium interaction with the same NaI(Tl) target detector. This 90% confidence level upper limit on WIMP-nucleon spin-independent cross section is 3.26*10^-4 pb for a WIMP mass at 10 GeV/c^2