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The shadow of a single atom

Take a laser (not a very powerful one, but still, emitting more light than a standard pointer) and shine the light on a single atom. Do you expect to see any effect? Even if the light is focused down to a waist of 1 micrometer, the size of an atom is one thousandth of that. So you would expect roughly 1/1000 of the light, or 0.1%, to be deflected. After all, you don't notice the shadow of mosquitoes flying against the lights of a stadium.

Still, if you choose your light well (right frequency, right polarization), the atom becomes like an antenna. Now, think of antennas on top of houses: they are quite small and thin, but they capture signals very well. The atom does the same: in our experiment, we proved that it captures 10% of the light! If you know some optics, you will also appreciate another of our results: in an interferometer, a single atom acts like a delay line that causes a change of phase by 1 degree.

Schematic of the single atom trap Photograph of the single atom trap

While we are working to improve the experiment and get even higher scattering rates, you can browse our publications and preprints:

  • The scattering experiment: M.K. Tey, Z. Chen, S.A. Aljunid, B.Chng, F. Huber, G. Maslennikov, C. Kurtsiefer, Nature Physics 4, 924-927 (2008); preprint available
  • The theoretical modelling: M.K. Tey, G. Maslennikov, T.C.H. Liew, S.A. Aljunid, F. Huber, B. Chng, Z. Chen, V. Scarani, C. Kurtsiefer, New J. Phys. 11, 043011 (2009)
  • The phase experiment: S.A. Aljunid, M.K. Tey, B. Chng, T.C.H. Liew, G. Maslennikov, V. Scarani, C. Kurtsiefer, preprint available
  • This work is also highlighted in New Scientist report

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