Towards a continuous superradiant laser on the strontium ¹S₀-³P₀ transition

Optical atomic clocks have achieved extraordinary precision, which makes them ideal for metrology, quantum sensing, and the exploration of new physics [1].  Superradiant lasers on the strontium 1S0-3P0 clock transition are promising frequency reference candidate for the next-generation of active optical atomic clocks [2]. 

While pulsed superradiant lasing on mHz-wide transition of 87Sr has been demonstrated [3], achieving steady-state operation is the next challenge for active optical clocks. We will describe a new machine that we are constructing based on our experience producing a continuous BEC of strontium [4, 5]. Our aim is to produce a continuously operating superradiant laser on the clock transition for use as a frequency standard. 

One of the main challenges for continuous superradiant emission is the production of a high flux beam of cold atoms [2]. We propose two different experimental designs to meet this requirement. In both cases an unceasing flux of atoms is guided into a ring cavity, where continuous superradiant emission will occur. In the first one, the atoms are provided by a continuous source based on our previous design [4, 5]. While in the second one they are conveyed from a reservoir, periodically refilled from a pulsed magneto-optical trap.  

  

[1] Safronova et al., Rev. Mod. Phys. 90, 025008 (2018). 

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

[3] Norcia et al., Sci. Adv. 2, e1601231 (2016).  

[4] Chen et al., Phys. Rev. Appl. 12, 044014 (2019). 

[5] Chen et al., arXiv:2012.07605 (2020).