Subradiant split Cooper pairs

TL;DR

This paper proposes a method to characterize the coherence of split Cooper pairs in a double-quantum-dot system by analyzing its microwave cavity emission, revealing nonmonotonic behavior linked to pair coherence.

Contribution

It introduces a novel approach using cavity QED techniques to assess the coherence of split Cooper pairs in quantum dot devices, which can be generalized to other nanoscale circuits.

Findings

Radiative response varies nonmonotonically with coupling parameters.

Coherence of split pairs influences the emitted radiation.

Method applicable to various nanoscale quantum circuits.

Abstract

We suggest a way to characterize the coherence of the split Cooper pairs emitted by a double-quantum-dot based Cooper pair splitter (CPS), by studying the radiative response of such a CPS inside a microwave cavity. The coherence of the split pairs manifests in a strongly nonmonotonic variation of the emitted radiation as a function of the parameters controlling the coupling of the CPS to the cavity. The idea to probe the coherence of the electronic states using the tools of Cavity Quantum Electrodynamics could be generalized to many other nanoscale circuits.