We will describe a next-generation active atomic frequency reference based on super-radiant pulses of laser light from the ultra-narrow, 1 mHz linewidth, optical clock transition in an ensemble of cold ⁸⁷Sr atoms. Light is stimulated from the millihertz linewidth transition by confining an ensemble of laser cooled atoms inside of a high finesse optical cavity. Such a light source has been proposed as a next-generation active atomic frequency reference, with the potential to enable high-precision optical frequency references to be used outside laboratory environments. We achieve a remarkable short term fractional frequency stability, 6.7 × 10¹⁶ at 1 s of averaging, absolute accuracy, 2 Hz (4 × 10¹⁵ fractional frequency), and high insensitivity to changes in the cavity length that limits the performance of todays more stable lasers. We will also discuss current work on cavity-enhanced dispersive measurements to perform high resolution spectroscopy and atom counting.

Date Published: 1 March 2019
PDF: 9 pages
Proc. SPIE 10934, Optical, Opto-Atomic, and Entanglement-Enhanced Precision Metrology, 109342B (1 March 2019); doi: 10.1117/12.2515582

Published in SPIE Proceedings Vol. 10934:
Optical, Opto-Atomic, and Entanglement-Enhanced Precision Metrology
Selim M. Shahriar; Jacob Scheuer, Editor(s)