Circuit qed enhanced magnetic resonance*

The detection and characterization of paramagnetic species by electron-spin resonance (ESR) spectroscopy has numerous applications. Most ESR spectrometers rely on the inductive detection of the small microwave signals emitted by the spins during their Larmor precession into a microwave resonator in which they are embedded. Using the tools offered by circuit Quantum Electrodynamics (QED), namely high quality factor superconducting micro-resonators and Josephson parametric amplifiers that operate at the quantum limit when cooled at 20mK [1], we investigate magnetic resonance in a new regime where the quantum nature of the microwave field plays a role. In particular, the spin detection sensitivity is strongly enhanced [2,3] and spin relaxation is governed by spontaneous emission through the cavity [4]. In this talk I will discuss applications of this new regime to high-sensitivity nuclear spin detection.
[1] X. Zhou et al., Physical Review B 89, 214517 (2014).
[2] A. Bienfait et al., Nature Nanotechnology 11(3), 253-257 (2016)
[3] S. Probst et al., to appear in APL (2017)
[4] A. Bienfait et al., Nature 531, 74 (2016)