Novel quantum phases in low-dimensional systems

Cristiane de Morais Smith

University of Utrecht, The Netherlands

I will discuss an experimental set-up recently proposed by us [1], which may allow for the realization of a staggered-flux phase in a 2D optical lattice loaded with bosons. The effective Hamiltonian of the system is a Bose-Hubbard one, with complex and anisotropic hopping coefficients. A very rich phase diagram emerges from the model: besides the usual Mott-insulator and zero-momentum condensate, a new phase with a finite momentum condensate becomes the ground-state at high-rotation [2]. An extension for fermionic atoms leads to an anisotropic Dirac spectrum, which is relevant to graphene and high-Tc superconductors [2].
[1] A. Hemmerich and C. Morais Smith, Phys. Rev. Lett. 99, 113002 (2007).
[2] Lih-King Lim, A. Hemmerich, and C. Morais Smith, Phys. Rev. Lett. 100, 130402 (2008).