A Minimal Nanowire-Based Kitaev Chain Using Proximitised Quantum Dots (Part 1)

Majorana bound states are highly sought-after quasi-particles, mainly due to their non-abelian statistics. This property is desirable both for fundamental research and possible applications in the field of quantum computing. The Kitaev model predicts that Majorana bound states appear at the ends of quantum dot-superconductor chains [1]. A two-site version of such a chain was reported recently [2]. Here, non-topological Majorana bound states appear when the system is tuned to a sweet spot. These Poor Man's Majoranas manifest themselves as zero bias conductance peaks and exhibit stability against local perturbations of the Majorana bound states, i.e. varying quantum dot energies in the chain [3]. Therefore, a finite energy splitting is expected when the system moves away from the sweet spot. Introducing a superconducting pairing in the quantum dots can increase reproducibility and stability of this sweet spot. We study Poor Man's Majoranas for different superconducting pairing versus charging energy ratios of the two quantum dots.

1. Sau, J. D., & Sarma, S. D. (2012). Realizing a robust practical Majorana chain in a quantum-dot-superconductor linear array. Nature communications, 3(1), 1-6.

2. Dvir, T., Wang, G., van Loo, N., Liu, C. X., Mazur, G. P., Bordin, A., ... & Kouwenhoven, L. P. (2022). Realization of a minimal Kitaev chain in coupled quantum dots. arXiv preprint arXiv:2206.08045.

3. Leijnse, M., & Flensberg, K. (2012). Parity qubits and poor man's Majorana bound states in double quantum dots. Physical Review B, 86(13), 134528.