for the financial support from the Academy of Finland (projects No. 263457 and No. 135135), the Magnus Ehrnrooth Foundation, the Finnish Cultural Foundation, Väisälä Foundation, FQXi, Centre of Quantum Engineering at Aalto University (project QMET), and the Centres of Excellence LTQ (project No. 250280) and COMP (projects No. 251748 and No. 284621). This work used the cryogenic facilities of the Low Temperature Laboratory at OtaNano/Aalto University.

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