5,519 research outputs found
Probabilistic teleportation of unknown two-particle state via POVM
We propose a scheme for probabilistic teleportation of unknown two-particle
state with partly entangled four-particle state via POVM. In this scheme the
teleportation of unknown two-particle state can be realized with certain
probability by performing two Bell state measurements, a proper POVM and a
unitary transformation.Comment: 5 pages, no figur
The IPAC-NC field campaign: a pollution and oxidization pool in the lower atmosphere over Huabei, China
In the past decades, regional air pollution characterized by photochemical smog and grey haze-fog has become a severe environmental problem in China. To investigate this, a field measurement campaign was performed in the Huabei region, located between 32–42° N latitude in eastern China, during the period 2 April–16 May 2006 as part of the project "Influence of Pollution on Aerosols and Cloud Microphysics in North China" (IPAC-NC). It appeared that strong pollution emissions from urban and industrial centers tend to accumulate in the lower atmosphere over the central area of Huabei. We observed widespread, very high SO<sub>2</sub> mixing ratios, about 20–40 ppbv at 0.5–1.5 km altitude and 10–30 ppbv at 1.5–3.0 km altitude. Average CO mixing ratios were 0.65–0.7 ppmv at 0.5–1.5 km altitude, and very high CO around 1 ppmv was observed during some flights, and even higher levels at the surface. We find the high pollution concentrations to be associated with enhanced levels of OH and HO<sub>2</sub> radicals, calculated with a chemical box model constrained by the measurements. In the upper part of the boundary layer and in the lower free troposphere, high CO and SO<sub>2</sub> compete with relatively less NO<sub>2</sub> in reacting with OH, being efficiently recycled through HO<sub>2</sub>, preventing a net loss of HO<sub>x</sub> radicals. In addition to reactive hydrocarbons and CO, the oxidation of SO<sub>2</sub> causes significant ozone production over Huabei (up to ~13% or 2.0 ppbv h<sup>−1</sup> at 0.8 km altitude). Our results indicate that the lower atmosphere over Huabei is not only strongly polluted but also acts as an oxidation pool, with pollutants undergoing very active photochemistry over this part of China
Optimal Controlled teleportation via several kinds of three-qubit states
The probability of successfully controlled teleportating an unknown qubit
using a general three-particle state is investigated. We give the analytic
expressions of maximal probabilities of successfully controlled teleportating
an unknown qubit via several kinds of tripartite states including a tripartite
GHZ state and a tripartite W-state.Comment: 15 page
Drinfel'd Realization of Quantum Affine Superalgebra
We obtain Drinfel'd's realization of quantum affine superalgebra
based on the super version of RS construction method and
Gauss decomposition
The emission positions of kHz QPOs and Kerr spacetime influence
Based the Alfven wave oscillation model (AWOM) and relativistic precession
model (RPM) for twin kHz QPOs, we estimate the emission positions of most
detected kHz QPOs to be at r=18+-3 km (R/15km) except Cir X-1 at r = 30\+-5 km
(R/15km). For the proposed Keplerian frequency as an upper limit to kHz QPO,
the spin effects in Kerr Spacetime are discussed, which have about a 5% (2%)
modification for that of the Schwarzchild case for the spin frequency of 1000
(400) Hz.The application to the four typical QPO sources, Cir X-1, Sco X-1, SAX
J1808.4-3658 and XTE 1807-294, is mentioned.Comment: Science China, Physics, Mechanics & Astronomy, 2010, 53, NO.
Constraints on Astro-unparticle Physics from SN 1987A
SN 1987A observations have been used to place constraints on the interactions
between standard model particles and unparticles. In this study we calculate
the energy loss from the supernovae core through scalar, pseudo scalar, vector,
pseudo vector unparticle emission from nuclear bremsstrahlung for degenerate
nuclear matter interacting through one pion exchange. In order to examine the
constraints on we considered the emission of scalar, pseudo
scalar, vector, pseudo vector and tensor through the pair annihilation process
. In addition we have re-examined other pair
annihilation processes. The most stringent bounds on the dimensionless coupling
constants for and are obtained from
nuclear bremsstrahlung process for the pseudo scalar and pseudo-vector
couplings and for
tensor interaction, the best limit on dimensionless coupling is obtained from
and we get .Comment: 12 pages, 2 postscript figure
High-Field Quasiparticle Tunneling in Bi_2Sr_2CaCu_2O_8+delta: Negative Magnetoresistance in the Superconducting State
We report on the c-axis resistivity rho_c(H) in Bi_2Sr_2CaCu_2O_{8+\delta}
that peaks in quasi-static magnetic fields up to 60 T. By suppressing the
Josephson part of the two-channel (Cooper pair/quasiparticle) conductivity
\sigma_c (H), we find that the negative slope of \rho_c(H) above the peak is
due to quasiparticle tunneling conductivity \sigma_q(H) across the CuO_2 layers
below H_{c2}. At high fields (a) \sigma_q(H) grows linearly with H, and (b)
\rho_c(T) tends to saturate (sigma_c \neq 0) as T->0, consistent with the
scattering at the nodes of the d-gap. A superlinear sigma_q(H) marks the normal
state above T_c.Comment: 4p., 5 fig. (.eps), will be published in Phys. Rev. Let
A Crucial Test for Color-Octet Production Mechanism in Z^0 Decays
The direct production rates of -wave charmonia in the decays of is
evaluated. The color-octet production processes are shown to have distinctively large branching ratios, the same order
of magnitude as that of prodution, as compared with other -wave
charmonium production mechanisms. This may suggest a crucial channel to test
the color-octet mechanism as well as to observe the -wave charmonium states
in decays. In addition, a signal for the charmonium as strong as
or with large transverse momentum at the Tevatron should
also be observed.Comment: 14 pages in LaTex (3 figures in PS-file
Thermodynamic properties of Ba1-xMxFe2As2 (M = La and K)
The specific heat of BaFeAs single crystal, electron-doped
BaLaFeAs and hole-doped BaKFeAs
polycrystals were measured. For undoped BaFeAs single crystal, a very
sharp specific heat peak was observed at 136 K. This is attributed to the
structural and antiferromagnetic transitions occurring at the same temperature.
of the electron-doped non-superconducting
BaLaFeAs also shows a small peak at 120 K, indicating a
similar but weaker structural/antiferromagnetic transition. For the hole-doped
superconducting BaKFeAs, a clear peak of was
observed at = 36 K, which is the highest peak seen at superconducting
transition for iron-based high- superconductors so far. The electronic
specific heat coefficient and Debye temperature of these
compounds were obtained from the low temperature data
- …