Affiliation
Delft University of Technology
Title of work
Majorana states in three-site Kitaev chains
Abstract
Majorana bound states (MBSs) are non-Abelian excitations predicted to emerge at the edges of topological superconductors. One proposal for realizing a topological superconductor in one dimension involves a chain of spinless fermions, coupled through p-wave superconducting pairing and electron hopping. This concept is known as the Kitaev chain. A minimal two-site Kitaev chain has recently been experimentally realized using quantum dots (QDs) coupled through a superconductor. In such a minimal chain, MBSs are quadratically protected against global perturbations of the QD electrochemical potentials; however, they are not protected from perturbations of the inter-QD couplings. Extending the chain to three sites offers greater protection than the two-site configuration. Here we demonstrate it by looking at the stability of the zero-energy modes, which is robust against variations in both the coupling amplitudes and the electrochemical potential variations in the constituent QDs. The enhanced protection of three-site chains is enabled by the "bulk" gap, signalling the onset of topology for quantum-dot-based Kitaev chains.