The double-slit experiment is one of the strongest pieces of evidence for the wave nature of light and it is also the best place to start to explore the key concepts of quantum physics. By this point, most teachers in Ontario are familiar with the great, free teaching resource from The Perimeter Institute of Theoretical called The Challenge of Quantum Reality. If you haven’t got yours yet, you should! Three short, on-line videos are now available as an addition to the resource.
Each video shows and example of the double-slit experiment with very different materials. In each case, we see individual dots appearing in random, but very specific locations. This means we can’t be looking at waves. However, over time they build up a clear interference pattern. This means that they can’t be classical particles. What are they? They are quantum objects which can’t be understood by any classical model but can be modelled very precisely by mathematics.
Photons: Double-slit Interference buildup
This video from the Institute of Quantum Computing shows what happens when extremely faint light is sent toward a double-slit. More details about this experiment and some other related ones involving polarization and entanglement can be found in their very interesting and surprisingly readable paper at http://arxiv.org/abs/1304.4943
Time-resolved double-slit experiment with entangled photons Piotr Kolenderski, Carmelo Scarcella, Kelsey D. Johnsen, Deny R. Hamel, Catherine Holloway, Lynden K. Shalm, Simone Tisa, Alberto Tosi, Kevin J. Resch, Thomas Jennewein, 6 May 2013
Electrons: Controlled Double-slit electron buildup
Controlled double-slit electron diffraction Roger Bach, Damian Pope, Sy-Hwang Liou and Herman Batelaan, New Journal of Physics, Volume 15, March 2013
Large Molecules: Real-time single-molecule imaging of quantum interference
This video of large molecule interference is from the Vienna group that was shown in The Challenge of Quantum Reality. These molecules in this experiment are huge! They are phythalocyanine (C32H18N8) which means they are made of 58 atoms — almost 800 electrons, neutrons and protons!. More details can be found in their paper but it costs $32, so I haven’t read it.
Real-time single-molecule imaging of quantum interference Thomas Juffmann, Adriana Milic, Michael Müllneritsch, Peter Asenbaum, Alexander Tsukernik, Jens Tüxen, Marcel Mayor, Ori Cheshnovsky & Markus Arndt, Nature Nanotechnology, July 2012