Probing the Jaynes-Cummings Ladder with Spin Circuit Quantum Electrodynamics

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.

Automated summary

We report on observations of transitions between excited states in the Jaynes-Cummings ladder of circuit quantum electrodynamics with electron spins (spin circuit QED). Unexplained features in recent experimental work are found to correspond to these transitions, and an input-output framework that incorporates these effects is presented. New experiments reproduce previous observations and demonstrate excited-state transitions and multiphoton transitions by increasing the probe power and using two-tone spectroscopy. The ability to probe the Jaynes-Cummings ladder is facilitated by improvements in the coupling-to-decoherence ratio, highlighting the increased maturity of spin circuit QED as an intriguing platform for studying quantum phenomena.