Flux-tunable Kitaev chain in a quantum dot array

Abstract

Connecting quantum dots through Andreev bound states in a semiconductor-superconductor hybrid provides a platform to create a Kitaev chain. Interestingly, in a double quantum dot, a pair of poor man's Majorana zero modes can emerge when the system is fine-tuned to a sweet spot, where superconducting and normal couplings are equal in magnitude. Control of the Andreev bound states is crucial for achieving this, usually implemented by varying its chemical potential. In this work, we propose using Andreev bound states in a short Josephson junction to mediate both types of couplings, with the ratio tunable by the phase difference across the junction. Now a minimal Kitaev chain can be easily tuned into the strong coupling regime by varying the phase and junction asymmetry, even without changing the dot-hybrid coupling strength. Furthermore, we identify an optimal sweet spot at $\pi$ phase, enhancing the excitation gap and robustness against phase fluctuations. Our proposal introduces a new device platform and a new tuning method for realizing quantum-dot-based Kitaev chains.

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Cited by in corpus (11)

• From perfect to imperfect poor man's Majoranas in minimal Kitaev chains
• Fate of poor man's Majoranas in the long Kitaev chain limit
• Majorana sweet spots in 3-site Kitaev chains
• 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
• A flux-controlled two-site Kitaev chain
• Braiding Majoranas in a linear quantum dot-superconductor array: Mitigating the errors from Coulomb repulsion and residual tunneling
• Properties and prevalence of false poor man's Majoranas in two- and three-site artificial Kitaev chains
• Quantifying robustness and locality of Majorana bound states in interacting systems
• Quantum capacitance and parity switching of a quantum-dot-based Kitaev chain
• Distinguishing Majorana bound states from accidental zero-energy modes with a microwave cavity