Two Slit's Cricket by Teachspin: Experiments

Two Slit's Cricket

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Cricket is intended for use with a "Two-Slit" apparatus which has been adjusted to deliver photon events at a low rate, for example 100/second, so that the mean time between events is 10 ms or longer. This will make the probability of two events overlapping very small. Then in the TeachSpin tradition of direct connection to the senses, students will get auditory access to individual photon events (the events which a counter would only sum). The clicks will be manifestly non-uniform in time since they correspond to individual, uncorrelated, random photon events. However, if the settings on the Two-Slit apparatus are changed, for instance, from one slit open to two slits open, the sound of the stream of clicks will immediately change.

With Cricket you can directly demonstrate the qualitative character of a series of individual quantum events, and can directly demonstrate the qualitative changes that ensue when you change settings in your Two-Slit apparatus. Our favorite demonstration is to open both slits, and find the central maximum of the two-slit interference pattern; then to move the detector slit so that we are at an adjacent minimum. Now we use the slit blocker to cover one of the two slits, cutting in half the total light coming down the apparatus. Nevertheless, the event rate audibly increases, as we have eliminated the destructive interference - but of what? These photons are clearly flying through the box one photon at a time!

Learn about Two Slit Interference, One Photon at a Time.