Parametric Light-Matter Interaction in the Single-Photon Strong Coupling Limit: Part I, Concept & Design

Parametric interactions between harmonic oscillators have enabled exquisite measurement precision and control, made possible by using strong sideband drives, enhancing the coupling rate while also linearizing the interaction. Here, we demonstrate parametric light-matter interaction in the field of circuit quantum electrodynamics. Our circuit implements a pure parametric, longitudinal coupling between the transmon qubit and a linear microwave resonator. A strong sideband drive results in an on-demand Jaynes-Cummings interaction with a high on-off ratio. We measure a single-photon coupling rate, an order of magnitude larger than all decay rates, placing the device in the highly sought single-photon strong coupling regime. The parametric light-matter interaction demonstrated here will enable the development of high-connectivity quantum information processing hardware and the exploration of the gravitational decoherence of quantum objects.

In the first part of this talk, we will introduce the longitudinal coupling method between the qubit and linear resonator and discuss the circuit implementation. In the second part, we will present the experimental realization of longitudinal qubit-resonator coupling by demonstrating an on-demand Jaynes-Cummings interaction and the achievement of single-photon strong coupling.