Non-Markovian effects in the Quantum noise of interacting nanostructures

TL;DR

This paper develops a quantum master equation approach to accurately describe finite-frequency noise in non-equilibrium, interacting nanostructures, emphasizing the importance of non-Markovian effects and initial correlations.

Contribution

It introduces a method to incorporate non-Markovian correlations in quantum noise analysis, crucial for high-frequency regimes in interacting systems.

Findings

Quantum-noise steps due to vacuum fluctuations are predicted at high frequencies.

Correct treatment of initial system-bath correlations is essential for accurate noise spectra.

The method successfully reproduces experimental counting statistics in quantum dots.

Abstract

We present a theory of finite-frequency noise in non-equilibrium conductors. It is shown that Non-Markovian correlations are essential to describe the physics of quantum noise. In particular, we show the importance of a correct treatment of the initial system-bath correlations, and how these can be calculated using the formalism of quantum master equations. Our method is particularly important in interacting systems, and when the measured frequencies are larger that the temperature and applied voltage. In this regime, quantum-noise steps are expected in the power spectrum due to vacuum fluctuations. This is illustrated in the current noise spectrum of single resonant level model and of a double quantum dot --charge qubit-- attached to electronic reservoirs. Furthermore, the method allows for the calculation of the single-time counting statistics in quantum dots, measured in recent experiments.