Optimal teleportation via thermal entangled states of a two-qubit Heisenberg Chain

We study the optimal teleportation based on Bell measurements via the thermal states of a two-qubit Heisenberg XXX chain in the presence of Dzyaloshinsky-Moriya (DM) anisotropic antisymmetric interaction and obtain the optimal unitary transformation. The explicit expressions of the output state and the teleportation fidelity are presented and compared with those of the standard protocol. It is shown that in this protocol the teleportation fidelity is always larger and unit fidelity is achieved at zero temperature. The DM interaction can enhance the teleportation fidelity at finite temperatures, as opposed to the effect of the interaction in the standard protocol. Cases with other types of anisotropies are also discussed.Comment: Accepted by EP

Switchable dual-wavelength erbium-doped fibre laser utilizing two-channel fibre Bragg grating fabricated by femtosecond laser

We propose and demonstrate a switchable dual-wavelength erbium-doped fibre ring laser. Competition between the lasing wavelengths in erbium-doped fibre laser at room temperature is suppressed by incorporating a two-channel fibre Bragg grating (TC-FBG), which consists of two highly localized sub-gratings fabricated by femtosecond laser in single mode fibre. Wavelengths and polarization states of the lasing lines are selected by the TC-FBG. Laser output can be switched between single- and dual-wavelength operations by simply adjusting the polarization controller. Stable dual-wavelength output is verified at room temperature with a power fluctuation less than 0.27 dB, and wavelength fluctuation less than 0.004 nm

Small-period long-period fiber grating with improved refractive index sensitivity and dual-parameter sensing ability

We UV inscribe and characterize a long-period fiber grating with a period of 25 μm. A series of polarization-dependent dual-peak pairs can be seen in the transmission spectrum, even though only the symmetrical refractive index modification is introduced. The fabricated grating exhibits a lower temperature sensitivity compared with standard long-period gratings and an enhanced refractive index sensitivity of ∼312.5 nm?RIU averaged from 1.315 to 1.395, which is more than four-fold higher than standard long-period gratings in this range. The full width at half-maximum of the fabricated grating is only about 0.6 nm, allowing for high-resolution sensing. Moreover, the grating period is so small that the attenuation dip corresponding to a high-order Bragg resonance can also be seen, which can act as a monitor of the unwanted perturbation to realize dual-parameter sensing

Anomalous wave propagation in quasiisotropic media

Based on boundary conditions and dispersion relations, the anomalous propagation of waves incident from regular isotropic media into quasiisotropic media is investigated. It is found that the anomalous negative refraction, anomalous total reflection and oblique total transmission can occur in the interface associated with quasiisotropic media. The Brewster angles of E- and H-polarized waves in quasiisotropic media are also discussed. It is shown that the propagation properties of waves in quasiisotropic media are significantly different from those in isotropic and anisotropic media.Comment: 15 pages, 4 figure

VASCULAR DYSFUNCTION IN THE Α-GALACTOSIDASE A-KNOCKOUT MOUSE IS AN ENDOTHELIAL CELL-, PLASMA MEMBRANE-BASED DEFECT

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75176/1/j.1440-1681.2008.04984.x.pd

catena-poly[[[(2,2′-bipyridine-2κ2 N,N′)-μ-cyanido-1:2κ2 N:C-cyanido-2κC-tris­(methanol-1κO)(nitrato-1κ2 O,O′)iron(II)yttrium(III)]-di-μ-cyanido-1:2′κ2 N:C;2:1′κ2 C:N] methanol solvate hemihydrate]

The title complex, {[FeIIYIII(CN)4(NO3)(C10H8N2)(CH3OH)3]·CH3OH·0.5H2O}n, is built up of ladder-like chains oriented along the c axis. Each ladder consists of two strands based on alternating FeII and YIII ions connected by cyanide bridges. Two such parallel chains are connected by additional cyanide anions (the ‘rungs’ of the ladder), which likewise connect FeII and YIII ions, such that each [Fe(bipy)(CN)4]2− (bipy is 2,2′-bipyridine) unit coordinates with three YIII ions and each YIII ion connects with three different [Fe(bipy)(CN)4]2− units. The FeII atom is six-coordinated in a distorted octa­hedral geometry and the YIII atom cation is eight-coordinated in a distorted dodeca­hedral environment. The uncoordinated methanol solvent mol­ecules are involved in hydrogen-bonding inter­actions with the one terminal cyanide group and a coordinated methanol mol­ecule from another [YIII(NO3)(CH3OH)3]2+ unit. Adjacent ladder-like chains are also held together by hydrogen bonds between the terminal cyanide ligands of the [Fe(CN)4(bipy)]2− units in one chain and the OH donors of CH3OH ligands from [YIII(NO3)(CH3OH)3] units in neighboring chains. The water molecule exhibits half-occupation

Self-Similar Shocks in Polytropic Gas Flows around Star-Forming Regions

Self-similar shock solutions in spherically symmetric polytropic gas flows are constructed and analyzed in contexts of proto-star formation processes. Among other possible solutions, we model a similarity shock across the sonic critical curve with an inner free-fall core collapse and a simultaneous outer expansion of the extended envelope; the separation or stagnation surface between these two flow zones travels outwards in a self-similar manner at a variable speed. One readily obtains accretion shock solutions. Semi-complete self-similar solutions across the sonic critical curve either once or twice without shocks can also be constructed. Features of star formation clouds of our polytropic model include the mass density scaling in the outer flow zone $\rho\propto r^{-2/(2-\gamma)}$, the temperature scalings of the inner flow zone $T\propto r^{-3(\gamma-1)/2}$ and of the outer flow zone $T\propto r^{-2(\gamma-1)/(2-\gamma)}$, and the variable central mass accretion rate $\dot{M}=k^{3/2}t^{(3-3\gamma)}m_0/G$ where $\gamma$ is the polytropic index, $k$ is a constant, $m_0$ is the core mass, and $G$ is the gravitational constant. Spectral line profiles characteristic of the `envelope expansion with core collapse' (EECC) shock solutions are expected. Random magnetic field permeated in a partially ionized cloud can be incorporated into this theoretical polytropic model framework. We discuss briefly our results in context of the oft-observed starless B335 cloud system as an example.Comment: 10 pages, 3 figures, accepted by MNRA

Molecular Line Profiles of Collapsing Gas Clouds

Emission line profiles of tracer molecule H$_2$CO 140 GHz transition from gravitational core collapsing clouds in the dynamic process of forming protostars are calculated, using a simple ray-tracing radiative transfer model. Three self-similar dynamic inside-out core collapse models -- the conventional polytropic model, the empirical hybrid model and the isothermal model -- for star-forming molecular clouds are examined and compared. The isothermal model cannot produce observed asymmetric double-peak molecular line profiles. The conventional polytropic model, which gives flow velocity, mass density and temperature profiles self-consistently, can produce asymmetric double-peak line profiles for a core collapsing cloud. In particular, the blue peak is stronger than the red peak, consistent with a broad class of molecular line profile observations. The relative strengths of the blue and red peaks within a molecular line profile are determined by the cloud temperature gradient. The conventional polytropic model can be utilized to produce molecular line-profile templates, for extracting dynamical information from line spectra of molecular globules undergoing a gravitational core collapse. We show a sample fit using the 140 GHz H$_2$CO emission line from the central region of the molecular globule B335 by our model with $\gamma=1.2$. The calculation of line profiles and fitting processes also offer a scenario to estimate the protostellar mass, the kernel mass accretion rate, and the evolution time scale of a core collapsing cloud. Our model can be readily adapted to other tracer molecules with more or less constant abundances in star-forming clouds.Comment: 12 pages, 10 figures, accepted for publication in MNRA