Series expansion of the quantum admittance in mesoscopic systems

The quantum admittance of an interacting/coupled mesoscopic system and its series expansion are obtained by using the refermionization method. With the help of these non-perturbative results, it is possible to study the dependencies of the admittance according to the applied dc voltage, temperature, and frequency without any restriction on the relative values of these variables. Explicit expressions of the admittance are derived both in the limits of weak and strong interactions/coupling strength, giving clear indication of the inductive or capacitive nature of the mesoscopic system. They help to determine the conditions under which the phase of the current with respect to the ac voltage is positive.Comment: 6 pages,3 figures, 1 tabl

Photo-assisted heat current and Peltier coefficient in a metal/dot/metal junction

The photo-assisted heat current through a metal/dot/metal junction and its associated Peltier coefficient are computed in the framework of the time-dependent out-of-equilibrium Keldysh formalism in the presence of a dot energy modulation. When the frequency of the modulation is much larger than the amplitude of the modulation, the heat current follows the sinusoidal time evolution of the dot energy. This is no longer the case when the modulation frequency becomes of the order or smaller than the amplitude of the modulation. To characterize this non sinusoidal behavior, we have calculated the harmonics of the photo-assisted heat current. The zero-order harmonic can be expressed as an infinite sum of dc heat currents associated to a dot with shifted energies. It exhibits a devil staircase profile with non horizontal steps whereas it is established that the steps are horizontal for the zero-order harmonic of the photo-assisted electric current. This particularity is related to the fact that the dot heat is not a conserved quantity due to energy dissipation within the tunnel barriers.Comment: Conference proceedin

Heat-charge mixed noise and thermoelectric efficiency fluctuations

The close relationship between the noise and the thermoelectric conversion is studied in a quantum dot using a quantum approach based on the non-equilibrium Green function technique. We show that both the figure of merit and the efficiency can be written in term of noise and we highlight the central role played by the correlator between the charge current and the heat current that we call the mixed noise. After giving the expression of this quantity as an integral over energy, we calculate it, first in the linear response regime, next in the limit of small transmission through the barriers (Schottky regime) and finally in the intermediate regime. We discuss the notion of efficiency fluctuations and we also see here that the mixed noise comes into play.Comment: Proceeding of the UPON 2015 conferenc

Getting information from the mixed electrical-heat noise

We give a classification of the different types of noise in a quantum dot, for variable temperature, voltage and frequency. It allows us first to show which kind of information can be extracted from the electrical noise, such as the ac-conductance or the Fano factor. And next, to classify the mixed electrical-heat noise, and to identify in which regimes information on the Seebeck coefficient, on the thermoelectric figure of merit, or on the thermoelectric efficiency can be obtained.Comment: Proceeding of the ICNF 2017 conference, IEEE, International Conference on Noise and Fluctuations (2017

Anomalous Hall effect and weak localization corrections in a ferromagnet

In this paper, we report results on the anomalous Hall effect. First, we summarize analytical calculations based on the Kubo formalism : explicit expressions for both skew-scattering and side-jump are derived and weak-localization corrections are discussed. Next, we present numerical calculations of the anomalous Hall resistivity based on the Dirac equation. Qualitative agreement with experiments is obtained.Comment: Proceeding JEMS'0

Electronic heat current fluctuations in a quantum dot

The fluctuations of the heat current in a quantum dot coupled to electron reservoirs are calculated at finite frequency, voltage and temperature using the nonequilibrium Green function technique. The non-symmetrized heat noise is expressed as an integral on energy containing four contributions, each of which includes transmission amplitudes, electron-hole pair distribution functions and energy difference factors. The effect of the asymmetry of the couplings between the quantum dot and the reservoirs is studied. Features of the heat noise are highlighted and discussed for an equilibrium and an out-of-equilibrium quantum dot. In the latter case and within the high transmission limit, the heat noise is closely related to the radiative power spectrum, leading to an out-of-equilibrium Planck's law. Proposals for the measurement of the heat noise are discussed.Comment: 7 pages, 4 figure

An electronic Mach-Zehnder interferometer in the Fractional Quantum Hall effect

We compute the interference pattern of a Mach-Zehnder interferometer operating in the fractional quantum Hall effect. Our theoretical proposal is inspired by a remarkable experiment on edge states in the Integer Quantum Hall effect (IQHE). The Luttinger liquid model is solved via two independent methods: refermionization at nu=1/2 and the Bethe Ansatz solution available for Laughlin fractions. The current differs strongly from that of single electrons in the strong backscattering regime. The Fano factor is periodic in the flux, and it exhibits a sharp transition from sub-Poissonian (charge e/2) to Poissonian (charge e) in the neighborhood of destructive interferences

Detection of finite frequency current moments with a dissipative resonant circuit

We consider the measurement of higher current moments with a dissipative resonant circuit, which is coupled inductively to a mesoscopic device in the coherent regime. Information about the higher current moments is coded in the histograms of the charge on the capacitor plates of the resonant circuit. Dissipation is included via the Caldeira-Leggett model, and it is essential to include it in order for the charge fluctuations (or the measured noise) to remain finite. We identify which combination of current correlators enter the measurement of the third moment. The latter remains stable for zero damping. Results are illustrated briefly for a quantum point contact

Fano factor, ΔT\Delta T-noise and cross-correlations in double quantum dots

We present a theoretical study of electrical current fluctuations and finite-frequency noise in a double quantum dot connected to two electron reservoirs with the aim of deriving the Fano factor, the $\Delta T$-noise and the cross-correlations. This allows one to highlight several interesting features. Firstly the possibility of getting a significant reduction of current noise and Fano factor either when the system is placed in a given operating regime, or when a temperature gradient is applied between the two reservoirs, resulting from the fact that a negative $\Delta T$-noise is generated. The second feature is the sign change found in the cross-correlator between the two reservoirs with increasing frequencies. This study clarifies the understanding of the results obtained experimentally in such systems.Comment: 5 pages, 6 figure