Observation of non-spreading wave packets in an imaginary potential

Authors:
  • RSR. Stuetzle
    R. Stuetzle
  • MGM. C. Goebel
    M. C. Goebel
  • THT. Hoerner
    T. Hoerner
  • EKE. Kierig
    E. Kierig
  • IMI. Mourachko
    I. Mourachko
  • MOM. K. Oberthaler
    M. K. Oberthaler
  • MEM. A. Efremov
    M. A. Efremov
  • MFM. V. Fedorov
    M. V. Fedorov
  • VYV. P. Yakovlev
    V. P. Yakovlev
  • KLK. A. H. van Leeuwen
    K. A. H. van Leeuwen
  • WSW. P. Schleich
    W. P. Schleich
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Abstract
We propose and experimentally demonstrate a method to prepare a non-spreading atomic wave packet. Our technique relies on a spatially modulated absorption constantly chiselling away from an initially broad de-Broglie wave. The resulting contraction is balanced by dispersion due to Heisenberg's uncertainty principle. This quantum evolution results in the formation of a non-spreading wave packet of Gaussian form with a spatially quadratic phase. Experimentally we confirm these predictions by observing the evolution of the momentum distribution. Moreover by employing interferometric techniques we measure the predicted quadratic phase across the wave packet. Non-spreading wave packets of this kind also exist in two space dimensions and we can control their amplitude and phase using optical elements.