Tunable photonic cavity coupled to a voltage-biased double quantum dot system: Diagrammatic NEGF approach

TL;DR

This paper develops a diagrammatic Keldysh NEGF approach to analyze microwave photonic cavities coupled to voltage-biased double quantum dots, demonstrating potential for signal amplification and photon source applications in hybrid quantum systems.

Contribution

It introduces a novel diagrammatic NEGF method for strongly coupled light-matter hybrid systems, enabling detailed analysis of gain and transport properties.

Findings

Achieves significant optical signal amplification using voltage-biased quantum dots.

Identifies elastic and inelastic tunneling processes involving the cavity mode.

Demonstrates potential for hybrid systems to function as single-atom amplifiers and photon sources.

Abstract

We investigate gain in microwave photonic cavities coupled to voltage-biased double quantum dot systems with an arbitrary strong dot-lead coupling and with a Holstein-like light-matter interaction, by adapting the diagrammatic Keldysh nonequilibrium Green's function approach. We compute out-of-equilibrium properties of the cavity : its transmission, phase response, mean photon number, power spectrum, and spectral function. We show that by the careful engineering of these hybrid light-matter systems, one can achieve a significant amplification of the optical signal with the voltage-biased electronic system serving as a gain medium. We also study the steady state current across the device, identifying elastic and inelastic tunnelling processes which involve the cavity mode. Our results show how recent advances in quantum electronics can be exploited to build hybrid light-matter systems that behave as single-atom amplifiers and photon source devices. The diagrammatic Keldysh approach is primarily discussed for a cavity-coupled double quantum dot architecture, but it is generalizable to other hybrid light-matter systems.