Seminarium Optyczne

So far Bose-Einstein condensates (BEC) and atom lasers have only been demonstrated as the products of a time-sequential, pulsed cooling sequence. For applications such as next generation atomic clocks,superradiant lasers or atom interferometers for gravitational wave detection, a steady-state source of quantumdegenerate atoms offers great advantages.However, the goal of producing a steady-state BEC or steady-state atom laser has long been thwartedby the incompatibility of laser cooling with evaporative cooling.In this talk, I will describe how we produced a steady-state Bose-Einstein condensate, that is, a BECwhose atom losses are continuously compensated, so that the BEC shows no signs of ever decaying. I willdetail our scheme’s key ingredients. Initially a spatially distributed architecture cools atoms using first thebroad 30-MHz and then the narrow 7.4-kHz strontium transitions in two spatially separated regions [1]. Wethen optically guide, transport, and slow these atoms [2, 3] to a region with very little resonant laser coolinglight. Finally, we protect this region using a “transparency beam” that Stark shifts atoms’ energy levels out ofresonance from the narrow cooling transition [4]. A BEC is thus formed, whose 3-body losses arecontinuously compensated by the pumping of new atoms.This open-dissipative BEC made from a dilute gas echoes the realizations of condensation withmagnons, excitons-polaritons and photons. As such, the study of its intensity and phase fluctuations will be acritical characterization of this continuous source of quantum degenerate matter. Finally, this could pointtoward the long-coveted path for the production of a cw atom laser.[1] S. Bennetts et al., Phys. Rev. Lett. 119, 223202 (2017).[2] C.-C. Chen et al., Phys. Rev. Appl 12, 044014 (2019).[3] C.-C. Chen et al., Phys. Rev. A 100, 023401 (2019).[4] S. Stellmer et al., Phys. Rev. Lett. 110, 263003 (2013)..