The Fermix Lab

The Fermix machine

Using laser and magnetic cooling and manipulation techniques, the Fermix machine brings a cloud of 40K down to the quantum degenerate regime where quantum mechanics dictates the macroscopic behaviour of the atoms. Using the so-called Feshbach resonance phenomenon, it is then possible to control the interactions between the atoms and to achieve a strongly interacting regime where quantum correlations are so strong that theoretical description becomes challenging even for state of the art numerical techniques.

One-dimensional fermions

Picture of an array of 1D Fermi gases. The distance between two tubes is 2.5µm and each tube contains typically a few hundred atoms

Many-body physics depends strongly on the dimensionality of the system and systems in lower dimensions differ radically from their 3D counterparts. In 1D systems, the strong topological constrains lead for instance to a suppressions of relaxation as a consequence of the existence of an infinite number of constant of motions (a phenomenon known as integrability). The Fermix experiment has recently been upgraded to allow for the exploration of 1D systems. Using an optical lattice, we create a series of strongly confined tubes where the transverse degrees of freddom are frozen. A high resolution imaging allows us to observe the tubes individually

From ultracold to ultrafast

It is possible to show that the dynamics of an ensemble of massive particles confined in linear magnetic trap is described by the same Hamiltonian as that of massless relativistic particles confined in a harmonic trap. We have shown that even in the absence of interactions, this system relaxes towards a equilibrium state that is only partially thermalized and keeps some memory of the excitation.

Poincaré's map of a particle in quadrupole trap.