E. Marechal

Nonequilibrium quantum magnetism in a dipolar lattice gas.

We report on the realization of quantum magnetism using a degenerate dipolar gas in an optical lattice. Our system implements a lattice model resembling the celebrated t-J model. It is characterized by a nonequilibrium spinor dynamics resulting from intersite Heisenberg-like spin-spin interactions provided by nonlocal dipole-dipole interactions. Moreover, due to its large spin, our chromium lattice gases constitute an excellent environment for the study of quantum magnetism of high-spin systems, as illustrated by the complex spin dynamics observed for doubly occupied sites.

All-Optical Production of Chromium Bose-Einstein Condensates

We report on the production of ^52Cr Bose Einstein Condensates (BEC) with an all-optical method. We first load 5.10^6 metastable chromium atoms in a 1D far-off-resonance optical trap (FORT) from a Magneto Optical Trap (MOT), by combining the use of Radio Frequency (RF) frequency sweeps and depumping towards the ^5S_2 state. The atoms are then pumped to the absolute ground state, and transferred into a crossed FORT in which they are evaporated. The fast loading of the 1D FORT (35 ms 1/e time), and the use of relatively fast evaporative ramps allow us to obtain in 20 s about 15000 atoms in an almost pure condensate.

Spontaneous Demagnetization of a Dipolar Spinor Bose Gas in an Ultralow Magnetic Field

We study the spinor properties of S = 3 (52)Cr condensates, in which dipole-dipole interactions allow changes in magnetization. We observe a demagnetization of the Bose-Einstein condensate (BEC) when the magnetic field is quenched below a critical value corresponding to a phase transition between a ferromagnetic and a nonpolarized ground state, which occurs when spin-dependent contact interactions overwhelm the linear Zeeman effect. The critical field is increased when the density is raised by loading the BEC in a deep 2D optical lattice. The magnetization dynamics is set by dipole-dipole interactions.

Simultaneous magneto-optical trapping of bosonic and fermionic chromium atoms

We report on magneto-optical trapping of fermionic 53Cr atoms. A Zeeman-slowed atomic beam provides loading rates up to 3 10^6 /s. We present systematic characterization of the magneto-optical trap (MOT). We obtain up to 5 10^5 atoms in the steady state MOT. The atoms radiatively decay from the excited P state into metastable D states, and, due to the large dipolar magnetic moment of chromium atoms in these states, they can remain magnetically trapped in the quadrupole field gradient of the MOT. We study the accumulation of metastable 53Cr atoms into this magnetic trap. We also report on the first simultaneous magneto-optical trapping of bosonic 52Cr and fermionic 53Cr atoms. Finally, we characterize the light assisted collision losses in this Bose-Fermi cold mixture.

A chromium dipolar Fermi sea

We report on the production of a degenerate Fermi gas of

Feshbach resonance in d -wave collisions

^{53}\mathrm{Cr}

Competition between Bose-Einstein Condensation and Spin Dynamics

atoms, polarized in the state

Accumulation of chromium metastable atoms into an optical trap

F=9/2, {m}_{F}=\ensuremath{-}9/2

Accumulation and thermalization of cold atoms in a finite-depth magnetic trap

, by sympathetic cooling with bosonic

Experimental study of excitations in a dipolar Bose-Einstein Condensate

S=3,\phantom{\rule{0.16em}{0ex}}{m}_{S}=\ensuremath{-}3 ^{52}\mathrm{Cr}