Regensburg 2022 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 1: Topology: Majorana Physics

TT 1.3: Vortrag

Montag, 5. September 2022, 10:15–10:30, H10

Cookbook for perfect topological Majorana fermions — •Prathyush P. Poduval^1,2, Thomas L. Schmidt¹, and Andreas Haller¹ — ¹University of Luxembourg, Luxembourg, Luxembourg — ²Indian Institute of Science, Bangalore, India

It has been demonstrated that Majorana corner modes of higher order topological insulators (HOTI) can be rotated by magnetic and superconducting pairing fields which pump the corner modes through the edges, and effectively realise a two-fold particle exchange [1]. These results are based on exact diagonalization of quadratic Hamiltonians that predict extended corner Majorana modes. Here, we show analytically that the topological phase of the 2D Majorana HOTI model can be adiabatically deformed to a scenario we dub "sweet spot limit", with perfectly localized Majorana corner modes. The existence of sweet spot limits are important for obtaining analytical solutions and also for possible experimental realizations with constraints on the total number of lattice nodes. Our findings are based on a systematic corner mode construction, which we apply to known lattice models in one and two spatial dimensions. The key idea is to obtain the typical lattice dimerization picture of the Hamiltonian matrix elements in a simultaneous eigenbasis of Majorana fermions and the symmetry operator which protects the corner modes. Based on our findings, we propose a novel 3D model featuring perfectly localized Majorana corner modes which avoids the dimensional obstruction encountered in 2D and may pave the way towards braiding.

[1] Phys. Rev. Res. 2, 032068