Abstract: We derive a general expression for the cumulant generating function (CGF) of non-Markovian quantum stochastic transport processes. The long-time limit of the CGF is determined by a single dominating pole of the resolvent of the memory kernel from which we extract the zero-frequency cumulants of the current using a recursive scheme. The finite-frequency noise is expressed not only in terms of the resolvent, but also initial system-environment correlations. As an illustrative example we consider electron transport through a dissipative double quantum dot for which we study the effects of dissipation on the zero-frequency cumulants of high orders and the finite-frequency noise.
Abstract: We investigate the current noise of a charge qubit coupled to a phonon bath in different parameter regimes. We find, using the theory of Full Counting Statistics of non-Markovian systems, that the current fluctuations are strongly influenced by memory effects generated from the interplay between quantum coherence and the dynamics of the phonon bath. (C) 2007 Elsevier B.V. All rights reserved.
Abstract: Current statistics of an antidot in the fractional quantum Hall regime is studied for Laughlin's series in the chiral Luttinger liquid picture of edge states with a renormalized interaction exponent. Universal sub-poissonian transport regimes are identified at low voltages through an analysis of higher current moments. A comparison between moments is proposed in order to clearly distinguish the charge of the carriers, regardless of possible non-universal interaction renormalizations. (C) 2007 Elsevier B.V. All rights reserved.
Abstract: Current statistics of an antidot in the fractional quantum Hall regime is studied for Laughlin's series. The chiral Luttinger liquid picture of edge states with a renormalized interaction exponent g is adopted. Several peculiar features are found in the sequential tunneling regime. On one side, current displays negative differential conductance and double-peak structures when g < 1. On the other side, universal sub-Poissonian transport regimes are identified through an analysis of higher current moments. A comparison between the Fano factor and skewness is proposed in order to clearly distinguish the charge of the carriers, regardless of possible nonuniversal interaction renormalizations. Super-Poissonian statistics is obtained in the shot limit for g < 1, and plasmonic effects due to the finite-size antidot are tracked.
Abstract: We consider the theoretical description of real-time counting of electrons tunneling through a Coulomb-blockade quantum dot using a detector with finite bandwidth. By tracing out the quantum dot we find that the dynamics of the detector effectively is non-Markovian. We calculate the cumulant generating function corresponding to the resulting non-Markovian rate equation and find that the measured current cumulants behave significantly differently compared to those of a Markovian transport process. Our findings provide a novel interpretation of noise suppression found in a number of systems.
Abstract: We present a theory of full counting statistics for electron transport through interacting electron systems with non-Markovian dynamics. We illustrate our approach for transport through a single-level quantum dot and a metallic single-electron transistor to second order in the tunnel coupling, and discuss under which circumstances non-Markovian effects appear in the transport properties.
Abstract: The statistics of tunneling current in a fractional quantum Hall sample with an antidot is studied in the chiral Luttinger liquid picture of edge states. A comparison between Fano factor and skewness is proposed in order to clearly distinguish the charge of the carriers in both the thermal and the shot limit. In addition, we address effects on current moments of nonuniversal exponents in single-quasiparticle propagators. Positive correlations, result of propagators behavior, are obtained in the shot noise limit of the Fano factor, and possible experimental consequences are outlined.
Abstract: The current-voltage characteristic of a one-dimensional quantum dot connected via tunnel barriers to interacting leads is calculated in the region of sequential tunneling. The spin of the electrons is taken into account. Non-Fermi liquid correlations implying spin-charge separation are assumed to be present in the dot and in the leads. It is found that the energetic distance of the peaks in the linear conductance shows a spin-induced parity effect at zero temperature T. The temperature dependence of the positions of the peaks depends on the non-Fermi liquid nature of the system. For nonsymmetric tunnel barriers negative differential conductances are predicted, which are related to the participation in the transport of collective states in the quantum dot with larger spins. Without spin-charge separation the negative differential conductances do not occur. Taking into account spin relaxation destroys the spin-induced conductance features. The possibility of observing in experiment the predicted effects are briefly discussed.
Abstract: Spin-charge states of correlated electrons in a one-dimensional quantum dot attached to interacting leads are studied in the nonlinear transport regime. With nonsymmetric tunnel barriers, regions of negative differential conductance induced by spin-charge separation are found. They are due to a correlation-induced trapping of higher-spin states without magnetic field and are associated with a strong increase in the fluctuations of the electron spin.
Abstract: The shot noise of a one-dimensional wire interrupted by two barriers shows interesting features related to the interplay between Coulomb blockade effects, Luttinger correlations, and discrete excitations. At small bias the Fano factor reaches the lowest attainable value, 1/2, irrespective of the ratio of the two junction resistances. At larger voltages this asymmetry is power-law renormalized by the interaction strength. We discuss how the measurement of current and these features of the noise allow to extract the Luttinger-liquid parameter.
Abstract: The ac-transport properties of a one-dimensional quantum dot with non-Fermi liquid correlations are investigated. It is found that the linear photoconductance is drastically influenced by the interaction. While for weak interaction it shows peak-like resonances, in the strong interaction regime it assumes a step-like behavior. In both cases the photo-transport provides precise informations about the quantized plasmon modes in the dot. Temperature and voltage dependences of the sideband peaks are treated in detail. Characteristic Luttinger liquid power laws are found.
Abstract: Spin effects in the transport properties of a quantum dot with spin-charge separation are investigated. It is found that the nonlinear transport spectra are dominated by spin dynamics. Strong spin polarization effects are observed in a magnetic field. They can be controlled by varying gate and bias voltages. Complete polarization is stable against interactions. When polarization is not complete it is power law enhanced by non-Fermi-liquid effects.
Abstract: The nonlinear transport properties of a single-channel quantum wire in the presence of two impurities are investigated. Treating the electron interaction within the Luttinger model, Coulomb oscillations and Coulomb staircase phenomena are identified. Several limiting cases of transport are discussed. The regime of temperatures smaller than the discretization energy of the charge density mode in the dot is treated in detail. For weak to intermediate interaction strengths, the nonlinear current exhibits a peculiar: step-like behavior related to the activation of excited plasmonic states. The corresponding differential conductance shows sharp peaks with non-analytic power law line-shape typical of Luttinger liquids.
Abstract: Current statistics of an antidot in the fractional quantum Hall regime is studied for Laughlin's series. The chiral Luttinger liquid picture of edge states with a renormalized interaction exponent $g$ is adopted. Universal sub-poissonian transport regimes are identified through an analysis of current cumulants in the sequential tunneling regime.
A comparison between noise and skewness is proposed in order to clearly distinguish the charge of the carriers, regardless of possible non-universal interaction renormalizations. Super-poissonian statistics is obtained in the shot limit for $g<1$, and
plasmonic effects due to the finite-size antidot are tracked.
