Mainz 2026 – wissenschaftliches Programm

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Q: Fachverband Quantenoptik und Photonik

Q 28: Poster – Quantum Optics

Q 28.19: Poster

Dienstag, 3. März 2026, 17:00–19:00, Philo 2. OG

(Quasi-)continuous-wave superradiant Lasers — •Max Hachmann, David Nak, and Andreas Hemmerich — Institut für Quantenphysik, Universität Hamburg, Deutschland

Superradiant Lasers are promising candidates for next-generation light sources with ultralow bandwidth, suitable as read-out tools for passive optical atomic clocks or active frequency standards themselves. Their main advantages are the possible utilization of ultranarrow transitions for lasing and a strongly suppressed dependence on an eigenfrequency of the laser cavity. However, achieving the full potential of sub-natural linewidths requires continuouswave operation, as pulsed emission is Fourier-limited.

We report the successful operation of a quasi-continuously emitting superradiant laser using cold bosonic calcium-40 atoms as the gain medium. These atoms are cooled in a bichromatic magneto-optical trap and loaded into a magic-wavelength one-dimensional optical lattice prepared inside a cavity. After incoherent population of the upper laser state, pulsed superradiant emission on the 370 Hz intercombination line was realized. We extended this scheme to continuously pump the decayed atoms back into the upper laser state, prolonging the lasing by up to three orders of magnitude until too many atoms are lost due to heating. We could observe a Fourier-limited but sub-natural emission linewidth of less than 100 Hz and confirmed suppressed cavity influence with a cavity pulling factor of only 0.5 %.

Keywords: superradiant laser; superradiance; calcium