Speaker
Prof.
Cristiane Morais Smith
(Utrecht University, The Netherlands)
Description
Abstract: I will discuss some properties of quantum Hall
fluids, more specifically the so-called topological insulators,
which exhibit a dissipation-less quantized spin-current. The
current is generated by a coupling between the spin and the
momentum of the electrons (spin-orbit interaction) and is
protected by a topological invariant, i.e., it depends only on
the topology of the material and not on its microscopic
details. This quantized Hall spin-current is analogous to the
quantized charge current that occurs in semiconductors, in
the quantum Hall regime [1]. The recent realization of
"synthetic graphene" by the self-assembling of
semiconducting nano-crystals into a honeycomb lattice has
opened new perspectives into the realization of topological
materials in condensed matter [2]. By choosing the
chemical elements in the nanocrystal, the spin-orbit
coupling can be tuned to a great extent, thus allowing us to
engineer new materials that could be useful for
technological applications. Topological states of matter are
being studied not only in condensed matter, but also in
quantum optics. By loading ultracold fermions or bosons
into optical lattices, it is possible to simulate cond-mat
systems, thus custom tailoring model Hamiltonians which
are supposed to describe complex quantum systems. The
recent experimental realization of a $p_x + i p_y$ Bose-
Einstein condensate of Rb in a 2D optical lattice, for which
time-reversal symmetry is spontaneously broken, is a
fascinating example of the numerous possibilities to be
explored with those systems [3].
[1] N. Goldman, W. Beugeling, and C. Morais Smith, EPL 97,
23003 (2012). [2] E. Kalesaki, C. Delerue, C. Morais Smith,
W. Beugeling, G. Allen, and D. Vanmaekelbergh, PRX 4,
011010 (2014). [3] M. Ölschläger, T. Kock, G. Wirth, A.
Ewerbeck, C. Morais Smith and A Hemmerich, New Journal
Phys.15, 083041 (2013).
