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Magnetic quantum gases (GQM)

> Magnetic quantum gases - Chromium

 

Magnetic quantum gases - Strontium

Isam Manai, Etienne Maréchal, Johnny Huckans, Olivier Gorceix, Paolo Pedri, Laurent Vernac, Bruno Laburthe-Tolra, Martin Robert-de-Saint-Vincent
Former members (Internships): R. Yenney, T. Nguyen, W. Dubosclard, A. Guittonneau, N. Auvray, M. Reboud

 

Large spin quantum gases with narrow line control

Quantum magnetism in ensembles of large spin atoms present possibilities beyond those offered by spin ½ electron gases and effective spin ½ atoms. For example, magnetic phases, with topological properties applicable to quantum information manipulation may be accessed, or new mechanisms for the emergence of superfluidity evidenced. Parallels to magnetic frustration can be drawn. We are building an experimental apparatus for the manipulation of ultracold fermionic gases of strontium 87, with large spin F = 9/2, disposed in periodic potentials with tunable topology. In addition to its high spin, Strontium 87 presents original interaction properties : contrary to most species (e.g., chromium), the interactions between two particles do not depend on their spin projections. Only the Pauli principle, that prevents direct interactions between two identical fermions, indirectly produces effective magnetic interactions. We aim at studying how entanglement and magnetic order depend on the interplay between lattice symmetry and the SU(N) symmetry associated to these spin-independent collision properties, from the familiar SU(2) case common to electrons to the unexplored regime where N>4.

 

A key ambition of ours is to take full advantage of the narrow lines of strontium, so precious to metrology, to devise original manipulation and measurement protocols. In particular, we are developing a super-resolution scheme using a narrow transition to measure the spin of each atom in each lattice site, with a quantum efficiency close to one. The spatial selectivity being based on the energy selectivity of the transition instead of an optical resolution, our scheme can achieve the record resolution suited for short-spacing lattices with fast magnetic dynamics, 3D selectivity, and full spin sensitivity at once. Furthermore, the built-in single-site adressing makes initial state preparation and single-spin manipulation readily available. It can also be used as a local drain, to explore open system dynamics. This approach bridges precision measurements and many-body physics, and overcomes one of the main challenges of the field today: to marry single site addressing and full spin sensitivity.

 

Single-site, spin-selective addressing, as a probe of magnetisation in a lattice...

Single-site, spin-selective addressing, as a probe of magnetisation in a lattice. We combine the efficiency of ion detection with the spin- and spatial-selectivity of a narrow line, in the presence of external magnetic and inhomogeneous laser fields. Here, atoms on sites are depicted as disks, spin state (mF) as colour. The detection here only occurs on the central lattice site and for spin mF (orange).

 

Contacts

Martin Robert-de-Saint-Vincent ou Etienne Maréchal

 

Fundings
CNRS
, UP13, DIM Nano’K – IFRAF, ANR, Labex FIRST-TF

 

References

  1. A. Gorshkov et al.,
    Two-orbital SU (N) magnetism with ultracold alkaline-earth atoms,
    Nature Physics 6, 289-295 (2010).

  2. C. Wu,
    Exotic many-body physics with large-spin Fermi gases,
    Physics 3, 92 (2010).

  3. G. Barontini et al,
    Controlling the Dynamics of an Open Many-Body Quantum System with Localized Dissipation,
    Phys. Rev. Lett. 110, 035302 (2013).

  4. J. P. Brantut et al.,
    Light-shift tomography in an optical-dipole trap for neutral atoms,
    Phys. Rev. A 78, 031401 (2008).

 

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