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Bose-Einstein condensates (BEC)

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Bose-Einstein Condensates - Sodium

Thomas Badr, Romain Dubessy, Aurélien Perrin, Hélène Perrin, Joseph Seaward (doctorant)
Former members: Dany Ben Ali (PhD 2016), now at Integrytis, Vincent Lorent (now in BMS team)

 

General presentation
Bringing a dilute gas of atoms to very low temperatures gives access to its quantum characteristics. These are intrinsically linked to the dimensionality of the object studied. In particular, one-dimensional systems of interacting bosons have a very specific excitation spectrum. While its theoretical description by Lieb and Liniger's model is well documented, the observation of its characteristics still represents an experimental challenge nowadays. Our experiment aims to explore, depending on the interaction between particles, the physics of a single one-dimensional gas of sodium atoms trapped on the surface of an atom chip. This chip, made up of a silicon wafer on which microscopic gold wires are deposited, allows to produce very anisotropic magnetic traps to confine atoms. At sufficiently low temperatures and densities, the transverse degrees of freedom of these systems are frozen and the unidimensional regime is reached. In addition, a microwave field will allow the strength of the interactions to be tuned. The experimental set-up is currently being set up and some recent results are presented below. For more information, please visit the team's page.

 

Experimental set-up
Cold atoms are prepared from an original source, a permanent magnet Zeeman slower. We studied in detail the polarization processes in the various internal states of sodium atom during the slowdown [1]. Our device allows us to produce clouds of cold atoms (figure 1a) very quickly and efficiently. These atoms are then transported to another part of the vacuum chamber containing the atom chip. This is currently being fabricated in Vienna as part of a collaboration. It features a microwave guide (figure 1b) whose field will allow to modify the interaction properties between atoms.

 

 

Figure: (a) Magneto-optical trap containing 109 sodium atoms. (b) design of the atom chip, with the microwave guide in the middle.

Figure: (a) Magneto-optical trap containing 109 sodium atoms. (b) design of the atom chip, with the microwave guide in the middle.

 

Contacts

Aurélien Perrin ou Hélène Perrin

 

Références

  1. Ben Ali D., Badr T., Brezillon T., Dubessy R., Perrin A., Perrin H.,
    Detailed study of a transverse field Zeeman slower,
    Journal of Physics B: Atomic, Molecular and Optical Physics, 50, 5, 055008, (2017)
    .

  2. Bücker R., Hohenester U., Berrada T., van Frank S., Perrin A., Manz S., Betz T., Grond J., Schumm T., Schmiedmayer J.,
    Dynamics of parametric matter wave amplification,
    Physical Review A, 86, 013638, (2012)
    .

  3. Perrin A., Bücker R., Manz S., Betz T., Koller C., Plisson T., Schumm T., Schmiedmayer J.,
    Hanbury Brown and Twiss correlations across the Bose–Einstein condensation threshold,
    Nature Physics, 8, 195–198, (2012)
    .

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