This title appears in the Scientific Report : 2015 

Exchange interaction of two spin qubits mediated by a superconductor
Hassler, Fabian
Catelani, Gianluigi (Corresponding author) / Bluhm, Hendrik
Theoretische Nanoelektronik; PGI-2
Physical review / B, 92 (2015) 23, S. 235401
College Park, Md. APS 2015
10.1103/PhysRevB.92.235401
Journal Article
Controlling Collective States
OpenAccess
OpenAccess
Please use the identifier: http://hdl.handle.net/2128/9553 in citations.
Please use the identifier: http://dx.doi.org/10.1103/PhysRevB.92.235401 in citations.
Entangling two quantum bits by letting them interact is the crucial requirement for building a quantum processor. For qubits based on the spin of the electron, these two qubit gates are typically performed by exchange interaction of the electrons captured in two nearby quantum dots. Since the exchange interaction relies on tunneling of the electrons, the range of interaction for conventional approaches is severely limited as the tunneling amplitude decays exponentially with the length of the tunneling barrier. Here, we present an approach to couple two spin qubits via a superconducting coupler. In essence, the superconducting coupler provides a tunneling barrier for the electrons which can be tuned with exquisite precision. We show that as a result exchange couplings over a distance of several microns become realistic, thus enabling flexible designs of multiqubit systems.