Laboratoire de Physique Théorique
Toulouse - UMR 5152

Cold atoms loaded in a tunable hexagonal optical lattice provide a new model system to study Dirac points [1]. By tuning the lattice parameters, Dirac points in the energy band structure can be manipulated by moving them and eventually, bringing them to a merging transition. The latter realizes a Lifshitz transition from a gapless phase with Dirac points to a gapped phase. To study such a system, Bloch-oscillation-type experiment has been performed with non-interacting fermionic atoms [1]. Here, we provide a quantitative description of the experiment within the framework of a universal Hamiltonian for the merging transition [2,3]. Moreover, we study signatures for the the corresponding atomic Stueckelberg interferometry.

[1] L. Tarruell, D. Greif, T. Uehlinger, G. Jotzu, T. Esslinger, Nature 483, 302 (2012) [2] G. Montambaux, F. Piechon, J.-N. Fuchs and M. O. Goerbig, Eur. Phys. J. B 72, 509 (2009) [3] L.-K. Lim, J.-N. Fuchs, G. Montambaux, Phys. Rev. Lett. 108, 175303 (2012)