LPL - Laboratoire de Physique des Lasers

Bose-Einstein condensates (BEC)

> Bose-Einstein Condensates - Sodium

 

Bose-Einstein Condensates - Rubidium

Thomas Badr, Romain Dubessy, Laurent Longchambon, Hélène Perrin, Avinash Kumar (post-doc), Mathieu de Goër de Herve (PhD), Yanliang Guo (PhD)
Former members: Camilla De Rossi (PhD 2016), now research engineer at VIRGO project (Cascina, Italy) Vincent Lorent (now in BMS team) Rudy Romain, post-doc 2015, Open University (UK) Karina Merloti (thèse 2013), consulting, Elée (Paris)

 

General presentation
When cooled at very low temperatures, a dilute atomic gas undergoes a phase transition that turns it into a macroscopic quantum object: a quantum gas, and more precisely (for rubidium) a Bose-Einstein condensate. To study its specific quantum properties, this gas can be contained in a wallless box (a "trap"), produced by laser beams and magnetic fields. Our group is expert in the manipulation of condensates in adiabatic traps, obtained by combining static and radio-frequency magnetic fields. Our current research is focused on the superfluity of these gases. The aim is to understand how superfluidity is modified when the gas is forced to evolve in dimension 2 or 1. You will find below some recent results. For more information, please visit the team page.

 

A two-dimensional quantum gas in a purely magnetic trap
We have successfully confined a quantum gas into two dimensions inside our adiabatic trap. The atomic motion is totally frozen in the vertical direction, while atoms are weakly confined in the horizontal directions. The trap is extremely smooth, making it ideal for the study of the collective modes of this two-dimensional quantum gas. Through a statistical analysis (principal component analysis) of the moving atom cloud images, we observed the shape of these first collective excitations of the Bogolubov spectrum. In addition, the scissors mode allowed us to determine locally the superfluid nature of the gas.

 

A superfluid rotating in a ring
The combination of the adiabatic trap with a laser makes it possible to create an atomic trap with an annular shape and an tunable radius (see figure). In this trap, a rotating superfluid would rotate continuously, without damping. This new setup constitutes a benchtest for superfluidity, especially relevant for studying superfluidity in dimension two.

 

 

Figure: Ultra cold rubidium atoms confined in a ring trap of tunable radius. (a) 20 micrometer radius. (b) 125 micrometer radius.

Figure: Ultra cold rubidium atoms confined in a ring trap of tunable radius. (a) 20 micrometer radius. (b) 125 micrometer radius.

 

Contacts

Hélène Perrin ou Laurent Longchambon

 

References

  1. Burrows K.A., Perrin H., Garraway B.M.,
    Non-adiabatic losses from radio-frequency dressed cold atom traps: beyond the Landau-Zener model,
    Physical Review A, 96, 023429, (2017)
    .

  2. De Rossi C., Dubessy R., Merloti K., de Goër de Herve M., Badr T., Perrin A., Longchambon L., Perrin H.,
    Probing superfluidity in a quasi two-dimensional Bose gas through its local dynamics,
    New Journal of Physics, Institute of Physics: Open Access Journals, 18, 062001, (2016)
    .

  3. Garraway B.M., Perrin H.,
    Recent developments in trapping and manipulation of atoms with adiabatic potentials,
    Journal of Physics B: Atomic, Molecular and Optical Physics, IOP Publishing, 49, 17, 172001, (2016)
    .

  4. Dubessy R., De Rossi C., Badr T., Longchambon L., Perrin H.,
    Imaging the collective excitations of an ultracold gas using statistical correlations,
    New Journal of Physics, 16, 122001, (2014)
    .

  5. Merloti K., Dubessy R., Longchambon L., Perrin A., Pottie P.-É., Lorent V., Perrin H.,
    A two-dimensional quantum gas in a magnetic trap,
    New Journal of Physics, 15, 033007, (2013)
    .

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