Spin-current injection and detection in strongly correlated organic conductor

Spin-current injection into an organic semiconductor $\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}$ film induced by the spin pumping from an yttrium iron garnet (YIG) film. When magnetization dynamics in the YIG film is excited by ferromagnetic or spin-wave resonance, a voltage signal was found to appear in the $\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}$ film. Magnetic-field-angle dependence measurements indicate that the voltage signal is governed by the inverse spin Hall effect in $\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}$. We found that the voltage signal in the $\rm{\kappa\text{-}(BEDT\text{-}TTF)_2Cu[N(CN)_2]Br}$/YIG system is critically suppressed around 80 K, around which magnetic and/or glass transitions occur, implying that the efficiency of the spin-current injection is suppressed by fluctuations which critically enhanced near the transitions

Origin of intrinsic dark count in superconducting nanowire single-photon detectors

The origin of the decoherence in superconducting nanowire single-photon detectors, the so-called dark count, was investigated. We measured the direct-current characteristics and bias-current dependencies of the dark count rate in a wide range of temperatures from 0.5 K to 4 K, and analyzed the results by theoretical models of thermal fluctuations of vortices. Our results indicate that the current-assisted unbinding of vortex-antivortex pairs is the dominant origin of the dark count.Comment: 10 pages, 2 figure

Model anisotropic quantum Hall states

Model quantum Hall states including Laughlin, Moore-Read and Read-Rezayi states are generalized into appropriate anisotropic form. The generalized states are exact zero-energy eigenstates of corresponding anisotropic two- or multi-body Hamiltonians, and explicitly illustrate the existence of geometric degrees of in the fractional quantum Hall effect. These generalized model quantum Hall states can provide a good description of the quantum Hall system with anisotropic interactions. Some numeric results of these anisotropic quantum Hall states are also presented.Comment: 10 pages, 5 figure

Scheme for remote implementation of partially unknown quantum operation of two qubits in cavity QED

By constructing the recovery operations of the protocol of remote implementation of partially unknown quantum operation of two qubits [An Min Wang: PRA, \textbf{74}, 032317(2006)], we present a scheme to implement it in cavity QED. Long-lived Rydberg atoms are used as qubits, and the interaction between the atoms and the field of cavity is a nonresonant one. Finally, we analyze the experimental feasibility of this scheme.Comment: 7 pages, 2 figure

Work Function of Single-wall Silicon Carbide Nanotube

Using first-principles calculations, we study the work function of single wall silicon carbide nanotube (SiCNT). The work function is found to be highly dependent on the tube chirality and diameter. It increases with decreasing the tube diameter. The work function of zigzag SiCNT is always larger than that of armchair SiCNT. We reveal that the difference between the work function of zigzag and armchair SiCNT comes from their different intrinsic electronic structures, for which the singly degenerate energy band above the Fermi level of zigzag SiCNT is specifically responsible. Our finding offers potential usages of SiCNT in field-emission devices.Comment: 3 pages, 3 figure