Full counting statistics of the photocurrent through a double quantum dot embedded in a driven microwave resonator

TL;DR

This paper analyzes the fluctuations and noise in the photocurrent of a double quantum dot system used as a microwave photon detector, revealing how detection efficiency affects current statistics and system behavior.

Contribution

It provides a theoretical study of photocurrent fluctuations and noise in a double quantum dot microwave photon detector, including analytical and numerical results, and explores the impact of detection efficiency.

Findings

Photocurrent fluctuations follow Poisson statistics at ideal detection efficiency.

Non-ideal detection results in sub-Poissonian photocurrent statistics.

Finite-frequency noise reveals system parameter dependencies.

Abstract

Detection of single, itinerant microwave photons is an important functionality for emerging quantum technology applications as well as of fundamental interest in quantum thermodynamics experiments on heat transport. In a recent experiment [W. Khan et al., Nat. Commun. 12, 5130 (2021)], it was demonstrated that a double quantum dot (DQD) coupled to a microwave resonator can act as an efficient and continuous photodetector by converting an incoming stream of photons to an electrical photocurrent. In the experiment, average photon and electron flows were analyzed. Here we theoretically investigate, in the same system, the fluctuations of the photocurrent through the DQD for a coherent microwave drive of the resonator. We consider both the low frequency full counting statistics as well as the finite-frequency noise (FFN) of the photocurrent. Numerical results and analytical expressions in limiting cases are complemented by a mean-field approach neglecting dot-resonator correlations, providing a compelling and physically transparent picture of the photocurrent statistics. We find that for ideal, unity efficiency detection, the fluctuations of the charge current reproduce the Poisson statistics of the incoming photons, while the statistics for non-ideal detection is sub-Poissonian. Moreover, the FFN provides information of the system parameter dependence of detector short-time properties. Our results give novel insight into microwave photon-electron interactions in hybrid dot-resonator systems and provide guidance for further experiments on continuous detection of single microwave photons.