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Exciting Andreev pairs in a superconducting atomic contact

An Erratum to this article was published on 18 December 2013

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Abstract

The Josephson effect describes the flow of supercurrent in a weak link—such as a tunnel junction, nanowire or molecule—between two superconductors1. It is the basis for a variety of circuits and devices, with applications ranging from medicine2 to quantum information3. Experiments using Josephson circuits that behave like artificial atoms4 are now revolutionizing the way we probe and exploit the laws of quantum physics5,6. Microscopically, the supercurrent is carried by Andreev pair states, which are localized at the weak link. These states come in doublets and have energies inside the superconducting gap7,8,9,10. Existing Josephson circuits are based on properties of just the ground state of each doublet, and so far the excited states have not been directly detected. Here we establish their existence through spectroscopic measurements of superconducting atomic contacts. The spectra, which depend on the atomic configuration and on the phase difference between the superconductors, are in complete agreement with theory. Andreev doublets could be exploited to encode information in novel types of superconducting qubits11,12,13.

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Figure 1: Principles of spectroscopy of the Andreev transition.
Figure 2: IJ(VJ) characteristics of the spectrometer coupled to the SQUID with atomic contact AC2.
Figure 3: Absorption spectra for three atomic contacts.
Figure 4: Interpretation of the absorption spectra.

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References

  1. Josephson, B. D. Possible new effects in superconductive tunnelling. Phys. Lett. 1, 251–253 (1962)

    Article  ADS  Google Scholar 

  2. Busch, S. et al. Measurements of T1-relaxation in ex vivo prostate tissue at 132 μT. Magn. Reson. Med. 67, 1138–1145 (2012)

    Article  ADS  Google Scholar 

  3. Erik Lucero et al. High-fidelity gates in a single Josephson qubit. Nature Phys. 8, 719–723 (2012)

  4. Wendin, G. & Shumeiko, V. S. Quantum bits with Josephson junctions. Low Temp. Phys. 33, 724–744 (2007)

    Article  CAS  ADS  Google Scholar 

  5. Fink, J. M. et al. Climbing the Jaynes–Cummings ladder and observing its nonlinearity in a cavity QED system. Nature 454, 315–318 (2008)

    Article  CAS  ADS  Google Scholar 

  6. Hofheinz, M. et al. Synthesizing arbitrary quantum states in a superconducting resonator. Nature 459, 546–549 (2009)

    Article  CAS  ADS  Google Scholar 

  7. Kulik, I. O. Macroscopic quantization and proximity effect in S-N-S junctions. Sov. Phys. JETP 30, 944–950 (1970)

    ADS  Google Scholar 

  8. Furusaki, A. & Tsukada, M. Dc Josephson effect and Andreev reflection. Solid State Commun. 78, 299–302 (1991)

    Article  ADS  Google Scholar 

  9. Beenakker, C. W. J. & van Houten, H. Josephson current through a superconducting quantum point contact shorter than the coherence length. Phys. Rev. Lett. 66, 3056–3059 (1991)

    Article  CAS  ADS  Google Scholar 

  10. Bagwell, P. F. Suppression of the Josephson current through a narrow, mesoscopic, semiconductor channel by a single impurity. Phys. Rev. B 46, 12573–12586 (1992)

    Article  CAS  ADS  Google Scholar 

  11. Zazunov, A., Shumeiko, V. S., Bratus’, E. N., Lantz, J. & Wendin, G. Andreev level qubit. Phys. Rev. Lett. 90, 087003 (2003)

    Article  CAS  ADS  Google Scholar 

  12. Chtchelkatchev, N. M. & Nazarov, V. Andreev quantum dots for spin manipulation. Phys. Rev. Lett. 90, 226806 (2003)

    Article  ADS  Google Scholar 

  13. Padurariu, C. & Nazarov, V. Spin blockade qubit in a superconducting junction. Europhys. Lett. 100, 57006–57011 (2012)

    Article  CAS  ADS  Google Scholar 

  14. Bardeen, J., Cooper, L. N. & Schrieffer, J. R. Theory of superconductivity. Phys. Rev. 108, 1175–1204 (1957)

    Article  MathSciNet  CAS  ADS  Google Scholar 

  15. Della Rocca, M. L. et al. Measurement of the current-phase relation of superconducting atomic contacts. Phys. Rev. Lett. 99, 127005 (2007)

    Article  CAS  ADS  Google Scholar 

  16. Zgirski, M. et al. Evidence for long-lived quasiparticles trapped in superconducting point contacts. Phys. Rev. Lett. 106, 257003 (2011)

    Article  CAS  ADS  Google Scholar 

  17. Deacon, R. S. et al. Tunneling spectroscopy of Andreev energy levels in a quantum dot coupled to a superconductor. Phys. Rev. Lett. 104, 076805 (2010)

    Article  CAS  ADS  Google Scholar 

  18. Pillet, J.-D. et al. Andreev bound states in supercurrent-carrying carbon nanotubes revealed. Nature Phys. 6, 965–969 (2010)

    Article  CAS  ADS  Google Scholar 

  19. Morpurgo, A. F., Baselmans, J. J. A., van Wees, B. J. & Klapwijk, T. M. Energy spectroscopy of the Josephson supercurrent. J. Low Temp. Phys. 118, 637–651 (2000)

    Article  CAS  ADS  Google Scholar 

  20. Fuechsle, M. et al. Effect of microwaves on the current-phase relation of superconductor normal-metal superconductor Josephson junctions. Phys. Rev. Lett. 102, 127001 (2009)

    Article  CAS  ADS  Google Scholar 

  21. van Ruitenbeek, J. M. et al. Adjustable nanofabricated atomic size contacts. Rev. Sci. Instrum. 67, 108–111 (1996)

    Article  CAS  ADS  Google Scholar 

  22. Edstam, J. & Olsson, H. K. Josephson broadband spectroscopy to 1 THz. Appl. Phys. Lett. 64, 2733–2735 (1994)

    Article  CAS  ADS  Google Scholar 

  23. Leppäkangas, J., Thuneberg, E., Lindell, R. & Hakonen, P. Tunneling of Cooper pairs across voltage-biased asymmetric single-Cooper-pair transistors. Phys. Rev. B 74, 054504 (2006)

    Article  ADS  Google Scholar 

  24. Billangeon, P.-M., Pierre, F., Bouchiat, H. & Deblock, R. Very high frequency spectroscopy and tuning of a single-Cooper-pair transistor with an on-chip generator. Phys. Rev. Lett. 98, 126802 (2007)

    Article  ADS  Google Scholar 

  25. Scheer, E., Joyez, P., Esteve, D., Urbina, C. & Devoret, M. H. Conduction channel transmissions of atomic-size aluminum contacts. Phys. Rev. Lett. 78, 3535–3538 (1997)

    Article  CAS  ADS  Google Scholar 

  26. Holst, T., Esteve, D., Urbina, C. & Devoret, M. H. Effect of a transmission line resonator on a small capacitance tunnel junction. Phys. Rev. Lett. 73, 3455–3458 (1994)

    Article  CAS  ADS  Google Scholar 

  27. Hofheinz, M. et al. Bright side of the Coulomb blockade. Phys. Rev. Lett. 106, 217005 (2011)

    Article  CAS  ADS  Google Scholar 

  28. Romero, G., Lizuain, I., Shumeiko, V. S., Solano, E. & Bergeret, F. S. Circuit quantum electrodynamics with a superconducting quantum point contact. Phys. Rev. B 85, 180506 (2012)

    Article  ADS  Google Scholar 

  29. Sköldberg, J., Löfwander, T., Shumeiko, V. S. & Fogelström, M. Spectrum of Andreev bound states in a molecule embedded inside a microwave-excited superconducting junction. Phys. Rev. Lett. 101, 087002 (2008)

    Article  ADS  Google Scholar 

  30. Mourik, V. et al. Signatures of Majorana fermions in hybrid superconductor-semiconductor nanowire devices. Science 336, 1003–1007 (2012)

    Article  CAS  ADS  Google Scholar 

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Acknowledgements

We acknowledge technical assistance from P. Sénat and P.-F. Orfila, theoretical input from M. Houzet, help in the experiments from L. Tosi, and discussions with V. Shumeiko, A. Levy-Yeyati and within the Quantronics group. This work was supported by ANR contracts DOCFLUC and MASH, and by C’Nano. The research leading to these results has received funding from the People Programme (Marie Curie Actions) of the European Union’s Seventh Framework Programme (FP7/2007-2013) under REA grant agreement no. PIIF-GA-2011-298415.

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All authors designed the experiment, L.B. and Ç.Ö.G. fabricated the sample, L.B., Ç.Ö.G., H.P. and C.U. carried out the measurements and analysed the data, and all authors contributed to the writing of the manuscript.

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Correspondence to C. Urbina.

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The authors declare no competing financial interests.

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This file contains Supplementary Figures 1-6, Supplementary Methods and additional references. (PDF 1217 kb)

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Bretheau, L., Girit, Ç., Pothier, H. et al. Exciting Andreev pairs in a superconducting atomic contact. Nature 499, 312–315 (2013). https://doi.org/10.1038/nature12315

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