Journal Article

FZJ-2021-00894

http://join2-wiki.gsi.de/foswiki/pub/Main/Artwork/join2_logo100x88.png Long-range exchange interaction between spin qubits mediated by a superconducting link at finite magnetic field

González Rosado, L.FZJ* ; Hassler, F. ; Catelani, G. (Corresponding author)FZJ*

2021
Inst. Woodbury, NY

This record in other databases:    

Please use a persistent id in citations: http://hdl.handle.net/2128/27095  doi:10.1103/PhysRevB.103.035430

Abstract: Solid-state spin qubits are promising candidates for the realization of a quantum computer due to their long coherence times and easy electrical manipulation. However, spin-spin interactions, which are needed for entangling gates, have only limited range as they generally rely on tunneling between neighboring quantum dots. This severely constrains scalability. Proposals to extend the interaction range generally focus on coherent electron transport between dots or on extending the coupling range. Here, we study a setup in which such an extension is obtained by using a superconductor as a quantum mediator. Because of its gap, the superconductor effectively acts as a long tunnel barrier. We analyze the impact of spin-orbit (SO) coupling, external magnetic fields, and the geometry of the superconductor. We show that while spin-nonconserving tunneling between the dots and the superconductor due to SO coupling does not affect the exchange interaction, strong SO scattering in the superconducting bulk is detrimental. Moreover, we find that the addition of an external magnetic field decreases the strength of the exchange interaction. Fortunately, the geometry of the superconducting link offers a lot of room to optimize the interaction range, with gains of over an order of magnitude from a two-dimensional (2D) film to a quasi-1D strip. We estimate that for superconductors with weak SO coupling (e.g., aluminum), exchange rates of up to 100 MHz over a micron-scale range can be achieved with this setup in the presence of magnetic fields of the order of 100 mT.

---

Contributing Institute(s):

1. JARA Institut Quanteninformation (PGI-11)

Research Program(s):

1. 522 - Quantum Computing (POF4-522) (POF4-522)
2. DFG project 387689860 - Langreichweitige Kopplung von Spin Quantenbits in Supraleiter-Halbleiter Heterostukturen (387689860)

Appears in the scientific report 2021

---

Database coverage:
; ; ; Clarivate Analytics Master Journal List ; Current Contents - Electronics and Telecommunications Collection ; Current Contents - Physical, Chemical and Earth Sciences ; Ebsco Academic Search ; Essential Science Indicators ; IF < 5 ; JCR ; SCOPUS ; Science Citation Index Expanded ; Web of Science Core Collection

---