Microwave spectroscopy on a double quantum dot with an on-chip Josephson oscillator

TL;DR

This paper demonstrates microwave spectroscopy on a double quantum dot using an on-chip Josephson oscillator, revealing photon-assisted tunnelling sidebands and comparing on-chip and external microwave sources.

Contribution

It introduces an on-chip Josephson oscillator as a microwave source for quantum dot spectroscopy, enabling integrated and potentially more scalable measurements.

Findings

Observation of photon-assisted tunnelling sidebands

Comparison between on-chip and external microwave sources

Successful implementation in AlGaAs/GaAs heterostructure

Abstract

We present measurements on microwave spectroscopy on a double quantum dot with an on-chip microwave source. The quantum dots are realized in the two-dimensional electron gas of an AlGaAs/GaAs heterostructure and are weakly coupled in series by a tunnelling barrier forming an 'ionic' molecular state. We employ a Josephson oscillator formed by a long Nb/Al-AlO$_x$/Nb junction as a microwave source. We find photon-assisted tunnelling sidebands induced by the Josephson oscillator, and compare the results with those obtained using an externally operated microwave source.