Imaging electron waves

R. M. Westervelt, M. A. Topinka, B. J. LeRoy, A. C. Bleszynski, K. Aidala, S. E.J. Shaw, E. J. Heller, K. D. Maranowski, A. C. Gossard

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


One can image the coherent flow of electron waves through a quantum point contact (QPC) into a two-dimensional electron gas by using scanning probe microscopy. A negatively charged tip depletes the electron gas below, backscatters electron waves, and reduces the QPC conductance. By raster scanning the tip over the sample, an image of electron flow is obtained. Images at liquid He temperatures show the individual quantum modes of the QPC. At greater distances, the electron flow forms narrow branches caused by small-angle scattering. Interference fringes in the images demonstrate the coherence of electron flow. An electron interferometer that acts as a quantum phase shifter was constructed by adding a gate to reflect electron waves back to the QPC, producing a V-shaped path for interfering electron waves with the apex at the QPC. When the length of one leg of the V is altered by changing the reflector gate voltage, the fringes at the other end of the V, under the tip, shift by the same distance. The interferometer is sensitive to transit time differences as small as ∼0.1ps between the two electron paths. These observations are in good agreement with theoretical simulations of electron flow.

Original languageEnglish (US)
Pages (from-to)63-69
Number of pages7
JournalPhysica E: Low-Dimensional Systems and Nanostructures
Issue number1-2 SPEC. ISS.
StatePublished - Aug 2004
EventProceedings of the Intenational Symposium on Functional - Atsugi/Kanagawa, Japan
Duration: Nov 12 2003Nov 14 2003


  • Imaging
  • Quantum point contact
  • Scanning probe microscopy
  • Two-dimensional electron gas

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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