Vortex spin qubits: Andreev spin qubits bound to Josephson vortices in spin-orbit coupled planar Josephson junctions

We introduce the Vortex Spin Qubit (VSQ), a novel Andreev Spin Qubit (ASQ) architecture realized in a planar superconductor-normal-superconductor (SNS) junction featuring a spin-orbit coupled 2DEG. A weak out-of-plane magnetic field induces a linear phase gradient and nucleates Josephson vortices hosting Andreev Bound States (ABSs). We show that the combination of the magnetic field and spin-orbit coupling stabilizes an odd-fermion parity ground state. This mechanism binds a single, isolated spinful low-energy degree of freedom to the vortex, which defines the VSQ. We detail operational protocols, including single-qubit gates via dynamic flux driving, the adaptation of established resonator-based readout strategies from conventional ASQs, and a framework for entangling two-qubit gates. By avoiding Zeeman fields and normal confinement, the VSQ offers reduced hardware overhead compared to standard ASQ implementations alongside new approaches for interconnectivity.