Shot Noise of Cotunneling Current

TL;DR

This paper investigates the noise characteristics of cotunneling currents in quantum dot systems, revealing universal behaviors, super-Poissonian noise in certain regimes, and interference effects in double-dot configurations.

Contribution

It provides a comprehensive analysis of cotunneling noise across different regimes and quantum dot configurations, including a non-equilibrium fluctuation-dissipation theorem and interference effects.

Findings

Universal noise-to-current ratio in weak cotunneling

Super-Poissonian noise due to state switching in strong inelastic cotunneling

Aharonov-Bohm effect observed in noise and current of double-dot systems

Abstract

We study the noise of the cotunneling current through one or several tunnel-coupled quantum dots in the Coulomb blockade regime. The various regimes of weak and strong, elastic and inelastic cotunneling are analyzed for quantum-dot systems (QDS) with few-level, nearly-degenerate, and continuous electronic spectra. In the case of weak cotunneling we prove a non-equilibrium fluctuation-dissipation theorem, which leads to a universal expression for the noise-to-current ratio (Fano factor). The noise of strong inelastic cotunneling can be super-Poissonian due to switching between QDS states carrying currents of different strengths. The transport through a double-dot (DD) system shows an Aharonov-Bohm effect both in noise and current. In the case of cotunneling through a QDS with a continuous energy spectrum the Fano factor is very close to one.