Spin bath maser in a cryogenically cooled sapphire whispering gallery mode resonator

Abstract

We report the observation of a mechanism of maser generation in an ensemble of inter-coupled, inhomogeneously broadened two-level systems, enhanced by high quality factor electromagnetic cavity modes. In this previously unobserved form of population inversion, an inseparable quantum system leads to cavity-enhanced stimulated emission arising from interactions within an ensemble of two-level systems, as opposed to a traditional ensemble of noninteracting identical three level systems. The effect is observed in a cryogenically cooled whispering gallery mode sapphire resonator containing dilute Fe${}^{3+}$ impurity ions. These ions exhibit strong spin-lattice interaction, leading to both electron spin resonance broadening and phonon mediated spin-spin coupling. The maser effect is due to a $|1/2⟩\to |3/2⟩$ energy transition in electron spin angular momentum observed at zero external magnetic field. Both continuous and oscillating regimes are observed with corresponding thresholds both in detuning frequency and incident power.

Phys. Rev. B, 2013

References in corpus (6)

• Cavity QED with an ultracold ensemble on a chip: prospects for strong magnetic coupling at finite temperatures
• Maser Oscillation in a Whispering-Gallery-Mode Microwave Resonator
• Measurement of fundamental thermal noise limit in a cryogenic sapphire frequency standard using bimodal maser oscillations
• Four Wave Mixing from Fe3+ Spins in Sapphire
• Hybrid Electron Spin Resonance and Whispering Gallery Mode Resonance Spectroscopy of Fe3+ in Sapphire
• Controlling the Frequency-Temperature Sensitivity of a Cryogenic Sapphire Maser Frequency Standard by Manipulating Fe3+ Spins in the Sapphire Lattice

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• Collective Behaviour of Cr${}^{3+}$ ions in Ruby Revealed by Whispering Gallery Modes
• Electromagnetic properties of terbium gallium garnet at millikelvin temperatures and single photon energy
• Magnetic sensitivity of the Microwave Cryogenic Sapphire Oscillator