Shot noise of photon-excited electron-hole pairs in open quantum dots

We investigate shot noise of photon-excited electron-hole pairs in open multi-terminal, multi-channel chaotic dots. Coulomb interactions in the dot are treated self-consistently giving a gauge-invariant expression for the finite frequency correlations. The Coulomb interactions decrease the noise, the strong interaction limit coincides with the non-interacting adiabatic limit. Inelastic scattering and dephasing in the dot are described by voltage and dephasing probe models respectively. We find that dephasing leaves the noise invariant, but inelastic scattering decreases correlations eventually down to zero.Comment: 4 pages, 1 figure; minor changes, 3 references adde

Shot Noise Current-Current Correlations in Multi-Terminal Diffusive Conductors

We investigate the correlations in the current fluctuations at different terminals of metallic diffusive conductors. We start from scattering matrix expressions for the shot noise and use the Fisher-Lee relation in combination with diagram technique to evaluate the noise correlations. Of particular interest are exchange (interference) effects analogous to the Hanbury Brown--Twiss effect in optics. We find that the exchange effect exists in the ensemble averaged current correlations. Depending on the geometry, it might have the same magnitude as the mean square current fluctuations of the shot noise. The approach which we use is first applied to present a novel derivation of the 1/3-suppression of shot noise in a two-terminal geometry, valid for an arbitrary relation between the length and wire width. We find that in all geometries correlations are insensitive to dephasing.Comment: 10 pages, two-column Revtex, 7 figures include

Electronic dephasing in wires due to metallic gates

The dephasing effect of metallic gates on electrons moving in one quasi--one--dimensional diffusive wires is analyzed. The incomplete screening in this geometry implies that the effect of the gate can be described, at high energies or temperatures, as an electric field fluctuating in time. The resulting system can be considered a realization of the Caldeira-Leggett model of an environment coupled to many particles. Within the range of temperatures where this approximation is valid, a simple estimation of the inverse dephasing time gives $\tau_{\rm G}^{-1} \propto T^{1/2}$.Comment: 6 page

Triplet Josephson effect with magnetic feedback

We study AC Josephson effect in a superconductor-ferromagnet heterostructure with a variable magnetic configuration. The system supports triplet proximity correlations whose dynamics is coupled to the magnetic dynamics. This feedback dramatically modifies the behavior of the junction. The current-phase relation becomes double-periodic at both very low and high Josephson frequencies $\omega_J$. At intermediate frequencies, the periodicity in $\omega_J t$ may be lost.Comment: 4 pages, 3 figure

Self-consistent theory of molecular switching

We study the model of a molecular switch comprised of a molecule with a soft vibrational degree of freedom coupled to metallic leads. In the presence of strong electron-ion interaction, different charge states of the molecule correspond to substantially different ionic configurations, which can lead to very slow switching between energetically close configurations (Franck-Condon blockade). Application of transport voltage, however, can drive the molecule far out of thermal equilibrium and thus dramatically accelerate the switching. The tunneling electrons play the role of a heat bath with an effective temperature dependent on the applied transport voltage. Including the transport-induced "heating" selfconsistently, we determine the stationary current-voltage characteristics of the device, and the switching dynamics for symmetric and asymmetric devices. We also study the effects of an extra dissipative environment and demonstrate that it can lead to enhanced non-linearities in the transport properties of the device and dramatically suppress the switching dynamics