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Register a new userFull counting statistics of strongly non-Ohmic transport through single molecules
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We study analytically the full counting statistics of charge transport through single molecules, strongly coupled to a weakly damped vibrational mode. The specifics of transport in this regime - a hierarchical sequence of avalanches of transferred charges, interrupted by quiet periods - make the counting statistics strongly non-Gaussian. We support our findings for the counting statistics as well as for the frequency-dependent noise power by numerical simulations, finding excellent agreement.
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A mesoscopic Coulomb blockade system with two identical transport channels is studied in terms of full counting statistics. It is found that the average current cannot distinguish the quantum constructive interference from the classical non-interference, but the shot noise and skewness are more sensitive to the nature of quantum mechanical interference and can fulfill that task. The interesting super-Poisson shot noise is found and is demonstrated as a consequence of constructive interference, which induces an effective system with fast-and-slow transport channels. Dephasing effects on the counting statistics are carried out to display the continuous transition from quantum interfering to non-interfering transports.
We examine the full counting statistics of electron transport through double quantum dots coupled in series, with particular attention being paid to the unique features originating from level renormalization. It is clearly illustrated that the energy renormalization gives rise to a dynamic charge blockade mechanism, which eventually results in super-Poissonian noise. Coupling of the double dots to an external heat bath leads to dephasing and relaxation mechanisms, which are demonstrated to suppress the noise in a unique way.
The complete characterisation of the charge transport in a mesoscopic device is provided by the Full Counting Statistics (FCS) $P_t(m)$, describing the amount of charge $Q = me$ transmitted during the time $t$. Although numerous systems have been theoretically characterized by their FCS, the experimental measurement of the distribution function $P_t(m)$ or its moments $langle Q^n rangle$ are rare and often plagued by strong back-action. Here, we present a strategy for the measurement of the FCS, more specifically its characteristic function $chi(lambda)$ and moments $langle Q^n rangle$, by a qubit with a set of different couplings $lambda_j$, $j = 1,dots,k,dots k+p$, $k = lceil n/2 rceil$, $p geq 0$, to the mesoscopic conductor. The scheme involves multiple readings of Ramsey sequences at the different coupling strengths $lambda_j$ and we find the optimal distribution for these couplings $lambda_j$ as well as the optimal distribution $N_j$ of $N = sum N_j$ measurements among the different couplings $lambda_j$. We determine the precision scaling for the moments $langle Q^n rangle$ with the number $N$ of invested resources and show that the standard quantum limit can be approached when many additional couplings $pgg 1$ are included in the measurement scheme.
The coherent potential approximation (CPA) within full counting statistics (FCS) formalism is shown to be a suitable method to investigate average electric conductance, shot noise as well as higher order cumulants in disordered systems. We develop a similar FCS-CPA formalism for phonon transport through disordered systems. As a byproduct, we derive relations among coefficients of different phonon current cumulants. We apply the FCS-CPA method to investigate phonon transport properties of graphene systems in the presence of disorders. For binary disorders as well as Anderson disorders, we calculate up to the $8$-th phonon transmission moments and demonstrate that the numerical results of the FCS-CPA method agree very well with that of the brute force method. The benchmark shows that the FCS-CPA method achieves $20$ times more speedup ratio. Collective features of phonon current cumulants are also revealed.
The internal dynamics of a double quantum dot system is renormalized due to coupling respectively with transport electrodes and a dissipative heat bath. Their essential differences are identified unambiguously in the context of full counting statistics. The electrode coupling caused level detuning renormalization gives rise to a fast-to-slow transport mechanism, which is not resolved at all in the average current, but revealed uniquely by pronounced super-Poissonian shot noise and skewness. The heat bath coupling introduces an interdot coupling renormalization, which results in asymmetric Fano factor and an intriguing change of line shape in the skewness.
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