Robust Spin Qubit Coupler via Minimal Kitaev Chain
arXiv:2607.11554
The paper proposes using a short Kitaev chain as a coupling element between spin qubits, where exchange interactions are mediated by Andreev bound states and can be tuned via the chemical potential to achieve strong coupling while being first-order insensitive to charge noise.
Abstract
While a minimal Kitaev chain is promised to host unprotected Majorana zero modes, its role for spin qubits is relatively underappreciated. Following recent breakthroughs in the fine control of transport behaviors, we propose to use minimal Kitaev chain as a robust coupling module between spin qubits. Long-distance, anisotropic exchange coupling can be mediated by the Andreev bound states (ABSs) in the hybrid segment. The chemical potential of ABS gives a simple way to selectively control the coupling strength and its response to local perturbations. Moreover, this additional control degree of freedom creates a unique sweet spot, allowing both strong coupling and first-order immunity against charge noise. The protected qubit encoded on the minimal Kitaev chain at the sweet spot is shown to boast over 200 fold improvement in decoherence time.