First-order topological quantum phase transitions in strongly correlated one-dimensional systems

Topological quantum phase transitions, such as the transition between a topological insulator and a trivial gapped phase, are hallmarked by the
change of a topological invariant [1]. For non-interacting fermions, such transitions between insulating phases are continuous since they are accompanied by the closing of the band gap as long as the symmetries of the system are maintained. For interacting fermions, by contrast, this paradigm is altered and first-order topological quantum transitions can occur [2].

In my talk I discuss the first example of a first-order topological quantum phase transition in a strongly correlated one-dimensional system [3].
Specifically, I consider a four-leg ladder which supports a symmetry protected topological phase in the presence of an on-site repulsive interaction, but is driven towards a trivial phase by a nearest-neighbor interaction. Employing a DMRG approach, I investigate at a numerically exact level the first-order nature of the transition.

References
[1] X. -L. Qi and S. -C. Zhang, Rev. Mod. Phys. 83, 1057 (2011).
[2] A. Amaricci, et al; Phys. Rev. Lett. 114, 185701 (2015).
[3] S. Barbarino, et al; in preparation.