Superconducting quantum circuits are now an established quantum technology that is at the heart of the largest scale commercial quantum computing platforms pursued and demonstrated to date. At the core of this technological platform is the Josephson junction which, together with inductors and capacitors on a chip, enable the engineering of strong single-photon nonlinearities, allowing one to explore unprecedented regimes of quantum physics and novel quantum applications.
In this talk, I will aim to give a pedagogical introduction to this platform, how it works, and discuss some of the recent work in my group exploring superconducting circuits for quantum sensing applications. In particular, I will present two examples from our efforts to extend circuit QED tools down to radio frequencies, with motivations of sensing and controlling radio frequency electromagnetic fields at the quantum level. While our motivation originated from applications in hybrid quantum systems with mechanical resonators, we believe this approach has exciting applications in many fields, including recent searches for axion dark matter candidates at radio-frequency energy scales.
In the first, I will present an approach based on ultra-strong light-matter interaction (99% of theoretical limit) to enable the sensing, cooling, and stabilisation of single photon states at MHz frequencies. In the second, I will present a new approach we have developed for coupling to MHz electrical circuits that we call “photon pressure”, inspired by and analogous to the optomechanical coupling implemented in LIGO, and show recent results cooling RF field to their quantum ground state and sensing RF fields with quantum-limited sensitivity.
References:
Observation and stabilization of photonic Fock states in a hot radio-frequency resonator
Mario F. Gely, Marios Kounalakis, Christian Dickel, Jacob Dalle, Rémy Vatré, Brian Baker, Mark D. Jenkins, Gary A. Steele
Science 363, 1072 (2019)
https://arxiv.org/abs/1901.07267
Photon-Pressure Strong-Coupling between two Superconducting Circuits
D.Bothner, I.C.Rodrigues, G.A.Steele
Nature Physics 17, 85 (2021)
https://arxiv.org/abs/1911.01262
Photon-pressure coupling with a hot radio-frequency circuit in the quantum regime
I.C. Rodrigues, D. Bothner, G.A. Steele