Current and noise expressions for radio-frequency single-electron transistors

Abstract

We derive self-consistent expressions of current and noise for single-electron transistors driven by time-dependent perturbations. We take into account effects of the electrical environment, higherorder co-tunneling, and time-dependent perturbations under the two-charged state approximation using the Schwinger-Kedysh approach combined with the generating functional technique. For a given generating functional, we derive exact expressions for tunneling currents and noises and present the forms in terms of transport coefficients. It is also shown that in the adiabatic limit our results encompass previous formulas. In order to reveal effects missing in static cases, we apply the derived results to simulate realized radio-frequency single-electron transistor. It is found that photon-assisted tunneling affects largely the performance of the single-electron transistor by enhancing both responses to gate charges and current noises. On various tunneling resistances and frequencies of microwaves, the dependence of the charge sensitivity is also discussed.

Finite-frequency current fluctuations and self-consistent perturbation theory for electron transport through a quantum dot

“…Actually, the functional approach has been applied to a wide range of problems in mesosocopic system in the literatures, e.g. current and noise characteristics for single-electron transistors in the Coulomb blockade regime 27,28 or the Kondo regime, 29 photoassisted shot noise in mesoscopic conductor, 2 charge transport to chaotic cavity 30 and the time evolution of nonequilibrium quantum dot system, 31 etc. This paper is organized as follows: In section II, we discuss the current conservation condition and the generalized Ward identity for quantum dot based on the Anderson impurity model.…”

Transport theory of coupled quantum dots based on the auxiliary-operator method

“…[22,23] With the fictitious fields, the evaluation of the generating functional is straightforward because bare Green's function is simply changed as,…”

“…The partition function in the grand canonical ensemble is calculated following the standard series expansion procedure. [23] Firstly, we integrate the action over Grassman variables {a * kασ , a kασ } and obtain…”

“…Here, the generalized partition function Z, in terms of the coherent path integral representation is given by, [22,23] …”

Green's function approach to transport through a gate-all-around Si nanowire under impurity scattering

“…¿From the generating functional technique as in Ref. [15], one can express the local electron density with the calculated Green's functions. The result reads,…”