Towards continuous superradiance with a thermal atomic beam

Continuous superradiant lasers have been proposed as next generation optical atomic clocks for precision measurement, metrology, quantum sensing and the exploration of new physics [1].

Superradiance is a collective phenomenon resulting in an enhanced single atom emission rate. A way to provide the required phase synchronization is to exploit a source of cold trapped atoms coherently coupled by a cavity-mediated interaction. Pulsed superradiance has been demonstrated with this technique [2], however steady-state operation remains an open challenge.

We will report on our machine aimed at validating the proposal for a rugged superradiant laser operating on the ¹S₀-³P₁ transition of ⁸⁸Sr using a hot collimated atomic beam [3]. The elegance of this approach is that a single cooling stage and a low finesse cavity appear sufficient to fulfill the requirements for continuous superradiance. Consequently, our device promises a compact, robust and simple optical frequency reference.

The nature of the superradiant phase transition still offers many open questions and drives ongoing studies.  As an outlook we will also elaborate on the potential of our machine as a platform with which to explore new exciting many-body phenomena [4].

[1] Meiser et al., Phys. Rev. Lett. 102, 163601 (2009)

[2] Norcia et al., Sci. Adv. 2, e1601231 (2016),  Schaffer et al., Phys. Rev. A 101, 013819 (2020)

[3] Liu et al., Phys. Rev. Lett. 125, 253602 (2020)

[4] Jäger et al., Phys. Rev. A 103, 013720 (2021)