Magnification of spin Hall effect in bilayer electron gas

Spin transport properties of a coupled bilayer electron gas with Rashba spin-orbit coupling are studied. The definition of the spin currents in each layer as well as the corresponding continuity-like equations in the bilayer system are given. The curves of the spin Hall conductivities obtained in each layer exhibit sharp cusps around a particular value of the tunnelling strength and the conductivities undergo sign changes across this point. Our investigation on the impurity effect manifests that an arbitrarily small concentration of nonmagnetic impurities does not suppress the spin Hall conductivity to zero in the bilayer system. Based on these features, an experimental scheme is suggested to detect a magnification of the spin Hall effect.Comment: Revtex 10 pages, 4 figures; largely extended versio

Understanding spin transport from the motion in SU(2)×\timesU(1) fields

Starting from a continuum constituted by charged tops, we formulate the classical counterpart of a previously obtained covariant continuity-like equation for the spin current. Such a formulism provides an intuitive picture to elucidate the non-conservation of the spin current and to interpret the condition for the emergence of an infinite spin relaxation time. It also facilitates the discussion on the spin precession in a one-dimensional quantum wire with Dresselhaus and Rashba spin-orbit couplings. Furthermore, we derive the diffusion equations for both the charge and spin densities and find that they couple to each other due to the Zitterbewegung.Comment: 6 pages, 4 figures; this is the extended version of Xiv:cond-mat/0608303 to publish in PR

Correlation between lasing and transport properties in a quantum dot-resonator system

We study a double quantum dot system coherently coupled to an electromagnetic resonator. By suitably biasing the system, a population inversion can be created between the dot levels. The resulting lasing state exists within a narrow resonance window, where the transport current correlates with the lasing state. It allows probing the lasing state via a current measurement. Moreover, the resulting narrow current peak opens perspective for applications of the setup for high resolution measurements.Comment: 4 pages, 4 figures; submitted to "Journal of Physics: Conference Series