Kitaev chain in an alternating quantum dot-Andreev bound state array

Abstract

We propose to implement a Kitaev chain based on an array of alternating normal and superconductor hybrid quantum dots embedded in semiconductors. In particular, the orbitals in the dot and the Andreev bound states in the hybrid are now on equal footing and both emerge as low-energy degrees of freedom in the Kitaev chain, with the couplings being induced by direct tunneling. Due to the electron and hole components in the Andreev bound state, this coupling is simultaneously of the normal and Andreev types, with their ratio being tunable by varying one or several of the experimentally accessible physical parameters, e.g., strength and direction of the Zeeman field, as well as changing proximity effect on the normal quantum dots. As such, it becomes feasible to realize a two-site Kitaev chain in a simple setup with only one normal quantum dot and one hybrid segment. Interestingly, when scaling up the system to a three-site Kitaev chain, next-nearest-neighbor couplings emerge as a result of high-order tunneling, lifting the Majorana zero energy at the sweet spot. This energy splitting is mitigated in a longer chain, approaching topological protection. Our proposal has two immediate advantages: obtaining a larger energy gap from direct tunneling and creating a Kitaev chain using a reduced number of quantum dots and hybrid segments.

12+6 pages, 7+4 figures

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Cited by in corpus (16)

• From perfect to imperfect poor man's Majoranas in minimal Kitaev chains
• Quantum-dot-based Kitaev chains: Majorana quality measures and scaling with increasing chain length
• Fate of poor man's Majoranas in the long Kitaev chain limit
• Interplay between Majorana and Shiba states in a minimal Kitaev chain coupled to a superconductor
• Majorana sweet spots in 3-site Kitaev chains
• Supercurrent through an Andreev trimer
• Interaction-induced strong zero modes in short quantum dot chains with time-reversal symmetry
• Scaling up a sign-ordered Kitaev chain without magnetic flux control
• Subgap states in semiconductor-superconductor devices for quantum technologies: Andreev qubits and minimal Majorana chains
• Braiding Majoranas in a linear quantum dot-superconductor array: Mitigating the errors from Coulomb repulsion and residual tunneling
• Phase-controlled minimal Kitaev chain in multiterminal Josephson junctions
• Characterizing local Majorana properties using Andreev states
• Properties and prevalence of false poor man's Majoranas in two- and three-site artificial Kitaev chains
• Distinguishing Majorana bound states from accidental zero-energy modes with a microwave cavity
• Quantum capacitance and parity switching of a quantum-dot-based Kitaev chain
• Optimal Majoranas in Mesoscopic Kitaev Chains