Probing the Jaynes-Cummings Ladder with Spin Circuit Quantum Electrodynamics

TL;DR

This paper demonstrates the observation of excited-state and multiphoton transitions in the Jaynes-Cummings ladder within spin circuit QED, highlighting advancements in experimental techniques and the platform's potential for quantum studies.

Contribution

It introduces an input-output framework accounting for these transitions and shows improved probing of the Jaynes-Cummings ladder in spin circuit QED.

Findings

Observation of excited-state transitions

Detection of multiphoton transitions

Enhanced coupling-to-decoherence ratio

Abstract

We report observations of transitions between excited states in the Jaynes-Cummings ladder of circuit quantum electrodynamics with electron spins (spin circuit QED). We show that unexplained features in recent experimental work correspond to such transitions and present an input-output framework that includes these effects. In new experiments, we first reproduce previous observations and then reveal both excited-state transitions and multiphoton transitions by increasing the probe power and using two-tone spectroscopy. This ability to probe the Jaynes-Cummings ladder is enabled by improvements in the coupling-to-decoherence ratio, and shows an increase in the maturity of spin circuit QED as an interesting platform for studying quantum phenomena.