Collective Behaviour of Cr${}^{3+}$ ions in Ruby Revealed by Whispering Gallery Modes

Abstract

We present evidence for collective action of Cr${}^{3+}$ ion impurities in a highly doped ruby crystal at microwave frequencies. The cylindrical geometry of the crystal allows for the creation of a superradiant, or "spin-mode" doublet, with spatial structure similar to that of microwave whispering gallery modes (WGMs). This results in a strict criteria of selection rules regarding the interaction of resonant WGMs and spin-modes; namely that only modes with the same wavenumber and azimuthal phase may interact. What results is an avoided level crossing between the two, in which both WGM doublet constituents are seen to interact with the spin resonance. We demonstrate that a four harmonic oscillator model is necessary to accurately describe this result.

5 pages, 5 figures

References in corpus (7)

• High Cooperativity Cavity QED with Magnons at Microwave Frequencies
• Observation of Dicke Superradiance for Two Artificial Atoms in a Cavity with High Decay Rate
• Anisotropic rare-earth spin ensemble strongly coupled to a superconducting resonator
• Cooperative Spontaneous Emission as a Many Body Eigenvalue Problem
• 3D Cavity quantum electrodynamics with a rare-earth spin ensemble
• Spin-Photon Interaction in a Cavity with Time-Reversal Symmetry Breaking
• Strong Coupling between Whispering Gallery Modes and Chromium Ions in Ruby

Cited by in corpus (2)

• Ultra-High Cooperativity Interactions between Magnons and Resonant Photons in a YIG sphere
• Spintronics with magnetic nanomolecules and graphene flakes