Search results for "CONDUCTIVITY"
showing 10 items of 1988 documents
Influence of magnetic field on cooling by normal-insulator–superconductor junctions
2000
Cooling by normal-insulator–superconductor junctions in external magnetic field has been studied experimentally. For all orientations of magnetic field the cooling performance correlates with the magnetic field dependent superconducting energy gap Δ(H). In perpendicular orientation of magnetic field with respect to the sample plane, additional degradation of the cooling power originates from scattering of nonequilibrium quasiparticles in the superconductor on magnetic vortices. The effect is hysteretic and its magnitude depends on the shape of the superconducting probes.
Decay chain information on the newly discovered double charm baryon state $\Xi_{cc}^{++}$
2017
We interprete the new double charm baryon state found by the LHCb Collaboration in the invariant mass distribution of the set of final state particles $(\Lambda_c^+\,K^-\,\pi^+\,\pi^+)$ as being at the origin of the decay chain $\Xi_{cc}^{++} \to \Sigma_c^{++} (\to \Lambda_c^+ \pi^+) +\bar K^{*0} (\to K^- \pi^+)$. The nonleptonic decay $\Xi_{cc}^{++} \to \Sigma_c^{++} + \bar K^{*0}$ belongs to a class of decays where the quark flavor composition is such that the decay proceeds solely via the factorizing contribution precluding a contamination from internal $W$-exchange. We use the covariant confined quark model previously developed by us to calculate the four helicity amplitudes that descri…
Dense Quark Matter in a Magnetic Field
2006
We explore the effects of an applied strong external magnetic field in the structure and magnitude of the color superconducting diquark condensate of a three massless flavor theory. The long-range component of the B field that penetrates the superconductor enhances the condensates formed by quarks charged with respect to this electromagnetic field.
Novel stripe textures in nonchiral hexatic liquid-crystal films
1992
A novel macroscopic stripe texture has been observed in freely suspended films of nonchiral liquid crystal, uniform stripes of alternating molecular orientation form spontaneously at the smectic-C--to--surface-hexatic phase transition and broaden with decreasing temperature. The stripes are identified as splay domains whose formation is attributed to the polar symmetry of the hexatic surface layers. Transverse (director bend) walls, which lead to an additional modulation of the basic one-dimensional pattern, are manifested inside thick circular islands as twelve-armed star defects.
Transfer coefficients for evaporation of a system with a Lennard-Jones long-range spline potential
2007
International audience; Surface transfer coefficients are determined by nonequilibrium molecular dynamics simulations for a Lennard-Jones fluid with a long-range spline potential. In earlier work A. Røsjorde et al., J. Colloid Interface Sci. 240, 355 2001; J. Xu et al., ibid. 299, 452 2006, using a short-range Lennard-Jones spline potential, it was found that the resistivity coefficients to heat and mass transfer agreed rather well with the values predicted by kinetic theory. For the long-range Lennard-Jones spline potential considered in this paper we find significant discrepancies from the values predicted by kinetic theory. In particular the coupling coefficient, and as a consequence the…
Converting external potential fluctuations into nonzero time-average electric currents using a single nanopore
2015
The possibility of taking advantage of a fluctuating environment for energy and information transduction is a significant challenge in biological and artificial nanostructures. We demonstrate here directional electrical transduction from fluctuating external signals using a single nanopore of conical shape immersed in an ionic aqueous solution. To this end, we characterize experimentally the average output currents obtained by the electrical rectification of zero time-average input potentials. The transformation of external potential fluctuations into nonzero time-average responses using a single nanopore in liquid state is of fundamental significance for biology and nanophysics. This energ…
Plenary talk - non coaxial force and inductance calculations for bitter coils and coils with uniform radial current distributions
2011
Recently the Bessel function approach to calculating the magnetic fields of coils has been used to calculate the mutual inductance and the force between two non coaxial thick cylindrical coils with parallel axes and uniform radial current distributions. This method can also be applied to calculate the force and inductance between an ordinary coil and a Bitter coil, or between two bitter coils, not necessarily coaxial. Bitter coils give a simpler case of the method, and it is possible to solve analytically for the magnetic field of a bitter disk.
Non coaxial force and inductance calculations for bitter coils and coils with uniform radial current distributions
2011
Recently the Bessel function approach to calculating the magnetic fields of coils has been used to calculate the mutual inductance and the force between two non coaxial thick cylindrical coils with parallel axes and uniform radial current distributions. This method can also be applied to calculate the force and inductance between an ordinary coil and a Bitter coil, or between two bitter coils, not necessarily coaxial. Bitter coils give a simpler case of the method, and it is possible to solve analytically for the magnetic field of a bitter disk.
Entanglement of superconducting qubits via microwave fields: Classical and quantum regimes
2008
We study analytically and numerically the problem of two qubits with fixed coupling irradiated with quantum or classical fields. In the classical case, we derive an effective Hamiltonian, and construct composite pulse sequences leading to a CNOT gate. In the quantum case, we show that qubit-qubit-photon multiparticle entanglement and maximally entangled two-qubit state can be obtained by driving the system at very low powers (one quanta of excitation). Our results can be applied to a variety of systems of two superconducting qubits coupled to resonators.
Macroscopic conductivity of free fermions in disordered media
2014
We conclude our analysis of the linear response of charge transport in lattice systems of free fermions subjected to a random potential by deriving general mathematical properties of its conductivity at the macroscopic scale. The present paper belongs to a succession of studies on Ohm and Joule's laws from a thermodynamic viewpoint. We show, in particular, the existence and finiteness of the conductivity measure $\mu _{\mathbf{\Sigma }}$ for macroscopic scales. Then we prove that, similar to the conductivity measure associated to Drude's model, $\mu _{\mathbf{\Sigma }}$ converges in the weak$^{\ast } $-topology to the trivial measure in the case of perfect insulators (strong disorder, compl…