1,720,983 research outputs found
Tuning excess noise by Aharonov-Bohm interferometry
No full textA voltage bias applied to a conductor induces a change of the current noise with respect to the equilibrium noise known as excess noise. We analyze the excess noise of the electronic current flowing through a mesoscopic Aharonov-Bohm ring threaded by a magnetic flux, coupled to a side gate, and contacted by two metallic electrodes. It is shown that the excess noise can be controlled both magnetically and electrostatically, demonstrating the full tunability of the system. At zero frequency, the ratio of the noise strength to the current (Fano factor) can thereby be minimized. Remarkably, at finite frequency, regions of negative excess noise emerg
La tectonique de plaques et l'Amazonie : Grabert H., Der Amazonas. Geschichte und Probleme eines Stromgebietes zwischen Pazifik und Atlantik
No full textTricart Jean L. F. La tectonique de plaques et l'Amazonie : Grabert H., Der Amazonas. Geschichte und Probleme eines Stromgebietes zwischen Pazifik und Atlantik. In: Annales de Géographie, t. 102, n°569, 1993. pp. 81-86
La tectonique de plaques et l'Amazonie : Grabert H., Der Amazonas. Geschichte und Probleme eines Stromgebietes zwischen Pazifik und Atlantik
No full textTricart Jean L. F. La tectonique de plaques et l'Amazonie : Grabert H., Der Amazonas. Geschichte und Probleme eines Stromgebietes zwischen Pazifik und Atlantik. In: Annales de Géographie, t. 102, n°569, 1993. pp. 81-86
Oscillatory nonlinear conductance of an interacting quantum wirewith an impurity
Full text linkThe nonlinear conductance of a one-dimensional quantum wire adiabatically coupled to Fermi liquid electron reservoirs is determined in the presence of an impurity. We show that electron-electron interaction in connection with the finite length of the wire leads to characteristic oscillations in the current as a function of the applied voltage
Appearance of fractional charge in the noise of nonchiral Luttinger liquids
Full text linkThe current noise of a voltage biased interacting quantum wire adiabatically connected to metallic leads is computed in the presence of an impurity in the wire. We find that in the weak backscattering limit the Fano factor characterizing the ratio between noise and backscattered current crucially depends on the noise frequency ω relative to the ballistic frequency vF/gL, where vF is the Fermi velocity, g is the Luttinger liquid interaction parameter, and L is the length of the wire. In contrast to chiral Luttinger liquids the noise is not only due to the Poissonian backscattering of fractionally charged quasiparticles at the impurity, but it also depends on Andreev-type reflections at the contacts, so that the frequency dependence of the noise needs to be analyzed to extract the fractional charge e*=eg of the bulk excitations
Electron tunneling into a quantum wire in the Fabry-Perot regime
Full text linkWe study a gated quantum wire contacted to source and drain electrodes in the Fabry-Pérot regime. The wire is also coupled to a third terminal (tip), and we allow for an asymmetry of the tip tunneling amplitudes of right-moving and left-moving electrons. We analyze configurations where the tip acts as an electron injector or as a voltage probe and show that the transport properties of this three-terminal setup exhibit very rich physical behavior. For a noninteracting wire we find that a tip in the voltage-probe configuration affects the source-drain transport in different ways, namely, by suppressing the conductance, by modulating the Fabry-Pérot oscillations, and by reducing their visibility. The combined effect of electron-electron interaction and finite length of the wire, accounted for by the inhomogeneous Luttinger liquid model, leads to significantly modified predictions as compared to models based on infinite wires. We show that when the tip injects electrons asymmetrically the charge fractionalization induced by interaction cannot be inferred from the asymmetry of the currents flowing in source and drain. Nevertheless interaction effects are visible as oscillations in the nonlinear tip-source and tip-drain conductances. Important differences with respect to a two-terminal setup emerge, suggesting new strategies for the experimental investigation of Luttinger liquid behavio
Negativity of the excess noise in a quantum wire capacitively coupled to a gate
Full text linkThe electrical current noise of a quantum wire is expected to increase with increasing applied voltage. We show that this intuition can be wrong. Specifically, we consider a single-channel quantum wire with impurities and with a capacitive coupling to nearby metallic gates and find that its excess noise, defined as the change in the noise caused by the finite voltage, can be negative at zero temperature. This feature is present both for large (c⪢cq) and small (c⪡cq) capacitive coupling, where c is the geometrical and cq the quantum capacitance of the wire. In particular, for c⪢cq, negativity of the excess noise can occur at finite frequency when the transmission coefficients are energy dependent—i.e., in the presence of Fabry-Pérot resonances or band curvature. In the opposite regime c≲cq, a nontrivial voltage dependence of the noise arises even for energy-independent transmission coefficients: at zero frequency the noise decreases with voltage as a power law when c<cq∕3, while, at finite frequency, regions of negative excess noise are present due to Andreev-type resonances
Transport properties of an interacting quantum wire with an impurity : Effects of the finite length
No full text- …
