Title: Making Quantum Liquids from Quantum Gases
When: Friday, 19th October, 2018, at 12:30.
Place: Sala de Seminarios, Módulo 03, Facultad de Ciencias, Universidad Autónoma de Madrid.
Speaker: Leticia Tarruell, ICFO – The Institute of Photonic Sciences, Castelldefels, Barcelona, Spain.
Self-bound states are ubiquitous in Nature and appear in contexts as diverse as solitary waves in channels, optical solitons in non-linear media, atomic nuclei and liquid droplets. Their binding results from a balance between attractive forces, which tend to make the system collapse, and repulsive ones, which stabilize it to a finite size. In my talk, I will present our recent experiments on dilute quantum liquid droplets: macroscopic clusters of ultra-cold atoms that are eight orders of magnitude more dilute than liquid Helium, but have similar liquid-like properties. We have observed for the first time these droplets in a mixture of Bose-Einstein condensates with effective attractive interactions, realizing a very unconventional liquid that does not fall into the standard Van der Waals paradigm, and mapped out the associated liquid-to-gas transition [C. R. Cabrera et al., Science 359, 301 (2018)].
In a second series of experiments, we have placed such droplets in an optical waveguide and explored their connection to more conventional bright solitons [P. Cheiney et al., Phys. Rev. Lett. 120, 135301 (2018) ]. Interestingly, the existence of dilute quantum droplets is a direct result of quantum fluctuations. Thus, their properties constitute a sensitive test of quantum many-body theories.