Letter | Published:

One minute parity lifetime of a NbTiN Cooper-pair transistor

Nature Physics volume 11, pages 547550 (2015) | Download Citation

Abstract

The parity modulation of the ground state of a superconducting island is a direct consequence of the presence of the Cooper-pair condensate preferring an even number of charge carriers1,2. The addition energy of an odd, unpaired quasiparticle equals the superconducting gap, Δ, suppressing single-electron hopping in the low-temperature limit, kBT Δ. Controlling the quasiparticle occupation is of fundamental importance for superconducting qubits as single-electron tunnelling results in decoherence3,4. In particular, topological quantum computation relies on the parity control and readout of Majorana bound states5,6. Here we present the first parity modulation of a niobium titanite nitride (NbTiN) Cooper-pair transistor coupled to aluminium (Al) leads. We show that this circuit is compatible with the magnetic field requirement B 100 mT of inducing topological superconductivity in spin–orbit-coupled nanowires7,8,9. Our observed parity lifetime exceeding 1 min is several orders of magnitude higher than the required gate time for flux-controlled braiding of Majorana states10.

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Acknowledgements

The authors thank A. R. Akhmerov, S. Rubbert, Y. Nazarov, R. Lutchyn and J. Pekola for fruitful discussions and R. N. Schouten for technical assistance. This work has been supported by the Netherlands Foundation for Fundamental Research on Matter (FOM) and Microsoft Corporation Station Q. A. G. acknowledges funding from the Netherlands Organisation for Scientific Research (NWO) through a VENI grant.

Author information

Author notes

    • David J. van Woerkom
    •  & Attila Geresdi

    These authors contributed equally to this work.

Affiliations

  1. QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600 GA Delft, The Netherlands

    • David J. van Woerkom
    • , Attila Geresdi
    •  & Leo P. Kouwenhoven

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Contributions

D.J.v.W. fabricated the devices. D.J.v.W. and A.G. performed the measurements. D.J.v.W., A.G. and L.P.K. discussed the data, contributed to the analysis and wrote the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Attila Geresdi.

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DOI

https://doi.org/10.1038/nphys3342

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