Giant photon gain in large-scale quantum dot circuit-QED systems

TL;DR

This paper explores how large-scale quantum dot circuit-QED systems can achieve giant microwave photon amplification, proposing scalable architectures and analyzing the underlying physical mechanisms for high gain.

Contribution

It introduces two scalable quantum dot architectures for achieving giant photon gain and explains the physical principles behind the amplification in these systems.

Findings

Demonstrates potential for giant microwave amplification in quantum dot systems.

Identifies charge response and cavity losses as key factors in photon gain.

Proposes scalable architectures for quantum amplification devices.

Abstract

Motivated by recent experiments on the generation of coherent light in engineered hybrid quantum systems, we investigate gain in a microwave photonic cavity coupled to quantum dot structures, and develop concrete directions for achieving a giant amplification in photon transmission. We propose two architectures for scaling up the electronic gain medium: (i) $N$ double quantum dot systems (N-DQD), (ii) $M$ quantum dots arranged in series akin to a quantum cascade laser setup. In both setups, the fermionic reservoirs are voltage biased, and the quantum dots are coupled to a single-mode cavity. Optical amplification is explained based on a sum rule for the transmission function, and it is determined by an intricate competition between two different processes: charge density response in the gain medium, and cavity losses to input and output ports. The same design principle is also responsible for the corresponding giant amplification in other photonic observables, mean photon number and emission spectrum, thereby realizing a quantum device that behaves as a giant microwave amplifier.