Disordered 2D gases

Lauriane Fouché, Guillaume Salomon, Pengjun Wang, Philippe Bouyer, Alain Aspect, Thomas Bourdel

The field and our experiment

Laser cooling and trapping of dilute atomic gases have led to an ultimate control of internal and motional quantum states of matter. Ultracold dilute gases are model quantum systems. In contrast with condensed matter systems, we are able to accurately control parameters, such as density, interaction, trap geometry, or even particle statistic.

In order to produce an utlracold atomic dilute sample, some cutting edge technologies are involved. We have built a compact and versatile apparatus to produce quantum gases of 87Rb and 39K. We rely on an all optical cooling scheme, which permits to reduce the duration of the experimental cycle to few seconds.

Our current research

We focus our research on the physics in two-dimensions in the presence of disorder. In 2D compared to 3D, the roles of interactions as well as quantum and thermal fluctuations are enhanced. For bosons, a specific superfluid phase transition occurs, called the Berezinskii-Kosterlitz-Thouless transition. In our system, the disorder is introduced in a controlled way through a speckle light field. In a sense, we thus simulate intrinsically disordered condensed matter systems such as thin metallic films or Hi-Tc superconductors for which the physics is only partly understood.

We first study the effect of disorder at the one particle level (i.e. without interaction). We can then observe classical trapping and diffusion, but also quantum phenomena such as weak and strong Anderson localization, which is the absence of diffusion due to interferences between scattering paths. 2D is the critical dimension for Anderson localization.

We also study the effect of disorder on the physics of interacting Bose gases. In such a many-body system, the competition between the interaction and the disorder leads to modification of the physics of the superfluid phase transition. Experimentally, we detect the phase coherence properties of the gas, which are modified at the phase transition. Moreover, for strong disorder and low temperatures, a transition to the elusive insulating Bose glass phase is expected.

Publications

• T. Bourdel, Phase diagrams of 2D and 3D disordered Boses gases in the local density approxiamtion, arXiv: 1210.1096
• T. Plisson, T. Bourdel, C.A. Müller, Momentum isotropisation in random potential, arXiv: 1209.1477
• B. Allard, T. Plisson, M. Holzmann, G. Salomon, A. Aspect, P. Bouyer, T. Bourdel, Effect of disorder close to the superfluid phase transition in a two-dimensional Bose gas. Phys. Rev. A 85, 033602 (2012).
• T. Plisson, B. Allard, M. Holzmann, G. Salomon, A. Aspect, P. Bouyer, T. Bourdel, Coherence properties of a 2D trapped Bose gas around the superfluid transition, Phys. Rev. A 84, 061606(R) (2011).
• T. Bourdel, M. Robert-de-Saint-Vincent, J.-P. Brantut, Ch. J. Borde, A. Aspect, P. Bouyer,
  Classical and quantum trampoline for ultra-cold atoms, in Quantum phenomena in gravitational field,
  Comptes Rendus Physique 12, 779 ( 2011).
• L. Pezze, M. Robert-de-Saint-Vincent, T. Bourdel, J.-P. Brantut, B. Allard, T. Plisson, A. Aspect, P. Bouyer, L. Sanchez-Palencia,
  Regimes of classical transport of cold gases in a two-dimensional anisotropic disorder,
  New Journal of Physics 13, 095015 (2011).
• M. Robert-de-Saint-Vincent, J.-P. Brantut, B. Allard, T. Plisson, L. Pezzé, L. Sanchez-Palencia, A. Aspect, T. Bourdel, P. Bouyer
  Anisotropic 2D diffusive expansion of ultra-cold atoms in a disordered potential
  Phys. Rev. Lett. 104, 220602 (2010).
• G. Stern, B. Allard, M. Robert-de-Saint-Vincent, J.-P. Brantut, B. Battelier, T. Bourdel, P. Bouyer
  A frequency doubled 1534 nm laser system for potassium laser cooling
  applied optics 49, 1 (2010).
• M. Robert-de-Saint-Vincent, J.-P. Brantut, Ch.J. Bordé, A. Aspect, T. Bourdel and P. Bouyer
  A quantum trampoline for ultra-cold atoms
  EPL 89, 10002 (2010).
• J.-F. Clément, J.-P. Brantut, M. Robert-de-Saint-Vincent, R. A. Nyman, A. Aspect, T. Bourdel, and P. Bouyer
  All-optical runaway evaporation to Bose-Einstein condensation
  Phys. Rev. A 79, 061406 (R) (2009)
• J. P. Brantut, J. F. Clément, M. Robert de Saint Vincent, G. Varoquaux, R.A. Nyman, A. Aspect, T. Bourdel, and P. Bouyer
  Light-shift tomography in an optical-dipole trap for neutral atoms
  Phys. Rev. A 78, 031401(R) (2008)
• G. Varoquaux, N. Zahzam, W. Chaibi, J.-F. Clément, O. Carraz, J.-P. Brantut, R.A. Nyman, F. Pereira Dos Santos, L. Mondin, M. Rouzé, Y. Bidel, A. Bresson, A. Landragin, P. Bouyer,
  I.C.E.: An Ultra-Cold Atom Source for Long-Baseline Interferometric Inertial Sensors in Reduced Gravity,
  eprint arXiv: 0705.2922, (2007) ; Rencontres de Moriond Gravitational Waves and Experimental Gravity
• R.A. Nyman, G. Varoquaux, F. Lienhart, D. Chambon, S. Boussen, J.F. Clément, T. Müller, G. Santarelli, F. Pereira Dos Santos, A. Clairon, A. Bresson, A. Landragin, P. Bouyer,
  I.C.E.: a transportable atomic inertial sensor for test in microgravity
  Applied physics B 84, 673 (2006)
• R. A. Nyman, G. Varoquaux, B. Villier, D. Sacchet, F. Moron, Y. Le Coq, A. Aspect, and P. Bouyer, Tapered-amplified AR-coated laser diodes for Potassium and Rubidium atomic-physics experiments
  Review of Scientific Instruments 77, 033105 (2006)

Offers of Projects for Undergraduates, PhDs and Post-docs

If you are interested in our research, please do not hesitate to contact Thomas Bourdel. We have open positions for PhD or post-docs. We also offer to some motivated undergraduate students at various levels to work with us every year. A link to a more detail thesis/intership proposition follows.

Former members of our team

• Baptiste Allard, now post-doc in Bale, Switzerland
• Thomas Plisson, now researcher in CEA
• Martin Robert-de-saint-Vincent; now Post-doc in Heidelberg, Deutchland
• Jean-Philippe Brantut, now Post-doc in Zürich, Switzerland
• Jean-Francois clément, now maitre de conférence in Phlam, Lille, France
• Robert Nyman, now Post-doc in Imperial College, London, Great Britain
• Gael Varoquaux, now in Neurospin, Saclay, France

Supports

• CNRS
• Université Paris 11
• ANR
• IFRAF
• DGA
• European Union through the euroquasar programm IQS
• European Union through the ERC (Quantatop)