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.

Dephasing in electron interference by a ‘which-path’ detector

Abstract

Wave–particle duality, as manifest in the two-slit experiment, provides perhaps the most vivid illustration of Bohr's complementarity principle: wave-like behaviour (interference) occurs only when the different possible paths a particle can take are indistinguishable, even in principle1. The introduction of a which-path (welcher Weg) detector for determining the actual path taken by the particle inevitably involved coupling the particle to a measuring environment, which in turn results in dephasing (suppression of interference). In other words, simultaneous observations of wave and particle behaviour is prohibited. Such a manifestation of the complementarity principle was demonstrated recently using a pair of correlated photons, with measurement of one photon being used to determine the path taken by the other and so prevent single-photon interference2. Here we report the dephasing effects of a which-path detector on electrons traversing a double-path interferometer. We find that by varying the sensitivity of the detector we can affect the visibility of the oscillatory interference signal, thereby verifying the complementarity principle for fermions.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.

from$8.99

All prices are NET prices.

Figure 1: The which-path device.
Figure 2: Conduction characteristics of the which-path device.
Figure 3: Measurements of visibility.

References

  1. 1

    Bohr, N. in Albert Einstein: Philosopher—Scientist (ed. Schilpp, P. A.) 200–241 (Library of Living Philosophers, Evanston, 1949).

    Google Scholar 

  2. 2

    Zou, X. Y., Wang, L. J. & Mandel, L. Induced coherence and indistinguishability in optical interference. Phys. Rev. Lett. 67, 318–321 (1991).

    ADS  CAS  Article  Google Scholar 

  3. 3

    Imry, Y. Introduction to Mesoscopic Physics (Oxford Univ. Press, 1997).

    Google Scholar 

  4. 4

    Stern, A., Aharonov, Y. & Imry, Y. Phase uncertainty and loss of interference: a general picture. Phys. Rev. A 41, 3436–3448 (1990).

    ADS  CAS  Article  Google Scholar 

  5. 5

    Schuster, R.et al. Phase measurement in a quantum dot via a double-slit interference experiment. Nature 385, 417–420 (1997).

    ADS  CAS  Article  Google Scholar 

  6. 6

    Van Houten, H., Beenakker, C. W. J. & Staring, A. A. W. in Single Charge Tunneling—Coulomb Blockade Phenomena in Nanostructures (eds Grabert, H. & Devoret, M. H.) Ch. 5 (Plenum, New York, 1992).

    Google Scholar 

  7. 7

    Gurvitz, S. A. Interaction free measurement in mesoscopic systems and the reduction postulate.Preprint available at http://xxx.lanl.gov/abs/quant-ph/9607029.

  8. 8

    Field, M.et al. Measurements of Coulomb blockade with a noninvasive voltage probe. Phys. Rev. Lett. 70, 1311–1314 (1993).

    ADS  CAS  Article  Google Scholar 

  9. 9

    Buttiker, M. Four terminal phase coherent conductance. Phys. Rev. Lett. 57, 1761–1764 (1986).

    ADS  CAS  Article  Google Scholar 

  10. 10

    Aronov, A. G. & Sharvin, Yu. V. Magnetic flux effects in disordered conductors. Rev. Mod. Phys. 59, 755–779 (1987).

    ADS  Article  Google Scholar 

  11. 11

    Aleiner, I. L., Wingreen, N. S. & Meir, Y. Dephasing and the orthogonality catastrophe in tunneling through a quantum dot: the “which path?” interferometer. Phys. Rev. Lett. 79, 3740–3743 (1997).

    ADS  CAS  Article  Google Scholar 

  12. 12

    Levinson, Y. Dephasing in a quantum dot due to coupling with a quantum point contact. Europhys. Lett. 39, 299–304 (1997).

    ADS  CAS  Article  Google Scholar 

  13. 13

    Gurvitz, S. A. Measurements with a noninvasive detector and dephasing mechanism. Phys. Rev. B 56, 15215–15223 (1997).

    ADS  CAS  Article  Google Scholar 

  14. 14

    Imry, Y. in Proc. 1997 Nobel Symp. on Modern Studies of Basic Quantum Concepts and Phenomena (in the press).

  15. 15

    Eglert, B. G. Fringe visibility and which-way information: an inequality. Phys. Rev. Lett. 77, 2154–2157 (1996).

    ADS  Article  Google Scholar 

  16. 16

    Khlus, V. A. Current and voltage fluctuations in microjunctions between normal metals and superconductors. JETP 66, 1243–1249 (1987).

    Google Scholar 

  17. 17

    Lesovik, G. B. Excess quantum noise in 2D ballistic point contacts. JETP Lett. 49, 592–594 (1989).

    ADS  Google Scholar 

Download references

Acknowledgements

We thank S. Gurvitz for presenting to us ref. 7, which initiated the present work. We also thank I. Imry, Y. Levinson, Y. Meir, A. Stern and N. Wingreen for discussions. This work was supported in part by a MINERVA grant and a MINERVA fellowship for one of us (R.S.).

Author information

Affiliations

Authors

Corresponding author

Correspondence to M. Heiblum.

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Buks, E., Schuster, R., Heiblum, M. et al. Dephasing in electron interference by a ‘which-path’ detector. Nature 391, 871–874 (1998). https://doi.org/10.1038/36057

Download citation

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

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