Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

  • Letter
  • Published:

Coherent control of macroscopic quantum states in a single-Cooper-pair box

Nature volume 398, pages 786–788 (1999)Cite this article

Abstract

A nanometre-scale superconducting electrode connected to a reservoir via a Josephson junction constitutes an artificial two-level electronic system: a single-Cooper-pair box. The two levels consist of charge states (differing by 2e, where e is the electronic charge) that are coupled by tunnelling of Cooper pairs through the junction. Although the two-level system is macroscopic, containing a large number of electrons, the two charge states can be coherently superposed1,2,3,4. The Cooper-pair box has therefore been suggested5,6,7 as a candidate for a quantum bit or ‘qubit’—the basic component of a quantum computer. Here we report the observation of quantum oscillations in a single-Cooper-pair box. By applying a short voltage pulse via a gate electrode, we can control the coherent quantum state evolution: the pulse modifies the energies of the two charge states non-adiabatically, bringing them into resonance. The resulting state—a superposition of the two charge states—is detected by a tunnelling current through a probe junction. Our results demonstrate electrical coherent control of a qubit in a solid-state electronic device.

This is a preview of subscription content, access via your institution

Access options

Buy this article

  • Purchase on Springer Link
  • Instant access to full article PDF
Buy now

Prices may be subject to local taxes which are calculated during checkout

Figure 1: Single-Cooper-pair box with a probe junction.
Figure 2: Pulse modulation of quantum states.
Figure 3: Effect of applying pulses as a function of d.c.-induced charge Q 0 and pulse length Δt.
Figure 4: Pulse-induced current as a function of the pulse length Δt.

Similar content being viewed by others

Article Open access 12 November 2022

Eric Hyyppä, Suman Kundu, … Mikko Möttönen

References

  1. Bouchiat, V., Vion, D., Joyez, P., Esteve, D. & Devoret, M. H. Quantum coherence with a single Cooper pair. Physica Scripta T 76, 165–170 (1998).

    Article  ADS  Google Scholar 

  2. Joyez, P., Lafarge, P., Filipe, A., Esteve, D. & Devoret, M. H. Observation of parity-induced suppression of Josephson tunneling in the superconducting single electron transistor. Phys. Rev. Lett. 72, 2458–2461 (1994).

    Article  ADS  CAS  Google Scholar 

  3. Flees, D., Han, S. & Lukens, J. Interband transitions and band gap measurements in Bloch transistors. Phys. Rev. Lett. 78, 4817–4820 (1997).

    Article  ADS  CAS  Google Scholar 

  4. Nakamura, Y., Chen, C. D. & Tsai, J. S. Spectroscopy of energy-level splitting between two macroscopic quantum states of charge coherently superposed by Josephson coupling. Phys. Rev. Lett. 79, 2328–2331 (1997).

    Article  ADS  CAS  Google Scholar 

  5. Shnirman, A., Schön, G. & Hermon, Z. Quantum manipulation of small Josephson junctions. Phys. Rev. Lett. 79, 2371–2374 (1997).

    Article  ADS  CAS  Google Scholar 

  6. Averin, D. V. Adiabatic quantum computation with Cooper pairs. Solid State Commun. 105, 659–664 (1998).

    Article  ADS  CAS  Google Scholar 

  7. Makhlin, Yu., Schön, G. & Shnirman, A. Josephson-junction qubits with controlled couplings. Nature 398, 305–307 (1999).

    Article  ADS  CAS  Google Scholar 

  8. Shedelbeck, G., Wegscheider, W., Bichler, M. & Abstreiter, G. Coupled quantum dots fabricated by cleaved edge overgrowth: from artificial atoms to molecules. Science 278, 1792–1795 (1997).

    Article  ADS  Google Scholar 

  9. Oosterkamp, T. H.et al. Microwave spectroscopy of a quantum-dot molecule. Nature 395, 873–876 (1998).

    Article  ADS  CAS  Google Scholar 

  10. Bonadeo, N. H.et al. Coherent optical control of the quantum state of a single quantum dot. Science 282, 1473–1476 (1998).

    Article  CAS  Google Scholar 

  11. Loss, D. & DiVincenzo, D. P. Quantum computation with quantum dots. Phys. Rev. A 57, 120–126 (1998).

    Article  ADS  CAS  Google Scholar 

  12. Kane, B. E. Asilicon-based nuclear spin quantum computer. Nature 393, 133–137 (1998).

    Article  ADS  CAS  Google Scholar 

  13. Leggett, A. J. in Chance and Matter(eds Souletie, J., Vannimenus, J. & Stora, R.) 395–506 (Elsevier, Amsterdam, (1984).

    Google Scholar 

  14. Tesche, C. D. Can a noninvasive measurement of magnetic flux be performed with superconducting circuits? Phys. Rev. Lett. 64, 2358–2361 (1990).

    Article  ADS  CAS  Google Scholar 

  15. Neumann, F., Ingold, G.-L. & Grabert, H. Influence of the environment on charge quantization in small superconducting islands. Phys. Rev. B 50, 12811–12819 (1994).

    Article  ADS  CAS  Google Scholar 

  16. Fulton, T. A., Gammel, P. L., Bishop, D. J., Dunkleberger, L. N. & Dolan, G. J. Observation of combined Josephson and charging effects in small tunnel junction circuits. Phys. Rev. Lett. 63, 1307–1310 (1989).

    Article  ADS  CAS  Google Scholar 

  17. Averin, D. V. & Aleshkin, V. Ya. Resonant tunneling of Cooper pairs in a system of two small Josephson junctions. JETP Lett. 50, 367–369 (1989).

    ADS  Google Scholar 

Download references

Acknowledgements

We thank W. Hattori, M. Baba and H. Suzuki for experimental help and M. Ueda, Y.Kohno, M. H. Devoret and Y. Ootuka for discussions. This work was supported by the Core Research for Evolutional Science and Technology (CREST) of the Japan Science and Technology Corporation (JST).

Author information

Authors and Affiliations

  1. NEC Fundamental Research Laboratories, Tsukuba, 305-8051, Ibaraki, Japan

    Y. Nakamura & J. S. Tsai

  2. CREST, Japan Science and Technology Corporation (JST), Kawaguchi, 332-0012, Saitama, Japan

    Yu. A. Pashkin

Authors
  1. Y. Nakamura
    View author publications

    You can also search for this author in PubMed Google Scholar

  2. Yu. A. Pashkin
    View author publications

    You can also search for this author in PubMed Google Scholar

  3. J. S. Tsai
    View author publications

    You can also search for this author in PubMed Google Scholar

Corresponding author

Correspondence to Y. Nakamura.

Rights and permissions

Reprints and permissions

About this article

Cite this article

Nakamura, Y., Pashkin, Y. & Tsai, J. Coherent control of macroscopic quantum states in a single-Cooper-pair box. Nature 398, 786–788 (1999). https://doi.org/10.1038/19718

Download citation

  • Received:

  • Accepted:

  • Issue Date:

  • DOI: https://doi.org/10.1038/19718

This article is cited by

Comments

By submitting a comment you agree to abide by our Terms and Community Guidelines. If you find something abusive or that does not comply with our terms or guidelines please flag it as inappropriate.

Search

Advanced search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing