Long-range coupling of spin qubits in superconductor-semiconductor hybrid structures
Final Report Abstract
The goal of this project has been to study the usefulness of superconductors in order to couple spin-qubits over long distances of the order of microns. Such couplings are essential to turn spin-qubits into a scalable architecture for a quantum computer. Superconductors are useful for this task as they shield against electromagnetic fields and disorder. Starting from the initial proposal, in the present project we have investigated realistic superconducting couplers, taking in particular disorder, spin-orbit coupling, and finite magnetic fields into account. To this end, we had to develop a novel theoretical method in order to describe diffusive quasiparticle transport in disordered superconductors. Building on this framework, we have investigated the feasibility and competitiveness of superconducting couplers. We have found that using a quasi 1D-coupler increased the strength of the exchange effects between two spin-qubits to a useful level, thus offsetting the detrimental effects of spin-orbit interaction and magnetic field. As a result, we judge superconducting couplers as a realistic avenue to couple spin-qubits, even though rather hard to realize experimentally.
Publications
- Mesoscopic effects in the heat conductance of superconducting-normal-superconducting and normal-superconducting junctions. Phys. Rev. B 99, 235422 (2019)
F. Hajiloo, F. Hassler, and J. Splettstoesser
(See online at https://doi.org/10.1103/PhysRevB.99.235422) - Weak localization corrections to the thermal conductivity in s-wave superconductors. Phys. Rev. B 101, 174202 (2020)
L. Gonzalez Rosado, F. Hassler, and G. Catelani
(See online at https://doi.org/10.1103/PhysRevB.101.174202) - Long-range exchange interaction between spin qubits mediated by a superconducting link at finite magnetic field. Phys. Rev. B 103, 035430 (2021)
L. Gonzalez Rosado, F. Hassler, and G. Catelani
(See online at https://doi.org/10.1103/PhysRevB.103.035430)
