Emergent quantum phenomena under peculiar disorder and non-trivial topology

Anantha Hegde, Adarsh Kumar, Adhip Agarwala +1 more

Xixi Feng, Ao Zhou, Feng Lu +2 more

We investigate the localization and topological properties of the non-equilibrium steady state (NESS) in a one-dimensional homogeneous system. Our results demonstrate that, despite the absence of disorder in the initial system, the NESS can exhibit localization under bond dissipation. These dissipation-driven localization and delocalization phenomena are clearly distinguished using Wigner distributions. Furthermore, we find that the initial localization characteristics of the system significantly influence the localization properties of the NESS. Drawing upon the concept of Bose-Einstein condensate broadening in cold-atom experiments, along with experimental data, we systematically characterize the impact of bond dissipation and disorder on the localization and topological properties of the NESS. The phase diagram reveals that the NESS can be topologically non-trivial even when the initial system is topologically trivial, and that the topological triviality of the initial system strengthens the topological non-triviality of the NESS. This work provides new insights into the localization and topological phase transitions in homogeneous systems induced by bond dissipation and disorder.

Vitor Dantas

Frustrated magnetism is a very active research topic in condensed matter physics. The competition between different ground states often leads to a suppression of the ordering temperature and opens up the possibility that novel states emerge. One state of particular interest are the spin liquids, for which we find no broken symmetry down to T —› 0, where T is the temperature. Moreover, theses states show topological order and are notable for their peculiar features, such as long-range entanglement and the emergence of fractionalized excitations. The Kitaev model is a fascinating example of an exactly solvable model displaying a spin-liquid ground state in two dimensions. In real materials, however, deviations from the original Kitaev model are expected to appear, and we discuss relevant perturbations here. In this work, we investigate the fate of Kitaevs spin-liquid in the presence of disorder bond defects or vacancies for an extended version of the model. Considering static flux backgrounds, we observe a power-law divergence in the low-energy limit of the density of states, with a non-universal exponent. We link this power-law distribution of energy scales to weakly coupled droplets inside the bulk, in an uncanny similarity to the Griffiths phase often present in the vicinity of disordered quantum phase transitions. If time-reversal symmetry is broken, we find that power-law singularities are tied to the destruction of the topological phase of the Kitaev model in the presence of bond disorder alone. For weak to moderate site dilution, there is a transition from this topologically trivial phase with power-law singularities to a topologically non-trivial one. Therefore, diluted Kitaev materials are potential candidates to host Kitaevs chiral spin-liquid phase.

Anantha Hegde, Adarsh Kumar, Adhip Agarwala +1 more

Anantha Hegde, Adarsh Kumar, Adhip Agarwala +1 more

Yiting Deng, Yan He

We study the two-dimensional disordered topological superconductor with Hubbard interactions. When the magnitude of the pairing potential is tuned to special values, this interacting model is exactly solvable even when disorders are imposed on the potential term or coupling constants. The topology of this model is investigated in detail by the real space Chern number formula, which computes the topological index of disordered systems to high precisions. It is found that the disorders can drive the system from topological trivial phase to a non-trivial phase, which generalizes the topological Anderson phenomena to interacting models. The self-consistent Born approximation is also employed to understand the influence of the disorders on the parameters of the interacting topological superconductor. It provide an alternative way to understand the topological transitions at weak disordered region.