Brief research summary over last 5 years / academic profile

Morais Smith is a theoretical physicist whose research interests range from condensed-matter to cold-atom systems. Research in her group spans a large variety of techniques, from tight-binding models to quantum field theory, renormalization group, Schwinger-Dyson, Hubbard Stratonovich, and Chern-Simons theory. She started her career working on quantum dissipative systems and high-Tc superconductors. Later, she worked on quantum Hall systems, graphene, and topological insulators.

One of her group’s recent highlights is the development of a platform for quantum simulations in electronic systems in a collaboration with Vanmaekelbergh and Swart (UU). The technique used is based on the pioneering works by Eigler and later Manoharan, who built artificial graphene by patterning CO molecules on the surface of Cu(111). Since one can only place the COs on top of the copper atoms, which have a triangular symmetry, it was not clear whether this approach could be used to build different lattices.

First, the Morais Smith/Vanmaekelbergh/Swart collaboration showed that one can also use this platform to build square and Lieb lattices [Nature Physics 2017]. Second, they demonstrated how to control the orbital (px and py) degrees of freedom. By appropriately engineering the lattice, it was possible to lift the degeneracy of the in-plane p-orbitals [PRX 2019, ACS Nano 2020]. Third, the group proved that one can not only control the geometry of the lattice, but also its dimensionality: they created three generations of a Sierpinski fractal to show theoretically and experimentally that the electronic wavefunction lives in 1.58 dimension [Nature Physics 2019]. This work was selected as a highlight in the Nature Physics-15 years celebration (2020). Fourth, the group provided the first experimental realization of a (dipolar) higher-order topological insulator with electrons [Nature Materials 2019]. They showed that the zero modes can be created and destroyed at will by introducing defects or protrusions into the lattice. Finally, four artificial Kekule lattices were built to show that in topological crystalline insulators the existence of topological states depends strongly on the termination of the sample [PRL 2020].

In the field of ultracold atoms, her work is marked by a longstanding collaboration with the experimental group of Hemmerich on quantum simulation of condensed-matter systems. Highlights include the proposal for the realization of an artificial gauge field in bichromatic optical lattices [PRL 2007, PRL 2008], and the interaction-driven p x +ip y phase of bosons in a bipartite optical lattice [NJP 2013]. The Morais Smith-Hemmerich group also revealed how phase coherence depends on structural transitions of the lattice [NatureComm 2014] and elucidated the topological character of the Varma phase [PRL 2016].

Besides the work on quantum simulations, the Morais Smith group has proposed a thermodynamic description of topological phase transitions and actively contributed to the development of a projected quantum electrodynamics (Pseudo QED) formulation to investigate topological phases driven by interactions [PRX 2015].