I got the idea last fall while building a supersimple cloud chamber. I was having trouble seeing particle tracks in my initial designs and wanted to check whether the radioactive materials I had scrounged really were radioactive. So I dug out a pair of Geiger counters that Aware Electronics in Wilmington, Delaware, gave me years ago for a post-9/11 review of consumer radiation detectors. Each time you hear a Geiger counter click, it has detected a single particle–which, in the case of gamma radiation, means a single high-energy photon. It struck me that the Geigers might substitute for the single-photon detectors that account for much of the cost of that EUR20,000 system.
Doing a literature survey, I found that the very first entanglement experiment, performed by Ernst Bleuler and H.L. Bradt and independently by R.C. Hanna in 1948, used Geigers. It was the precursor of better-known work by Chien-Shiung Wu and Irving Shaknov, who reproduced the results using more sensitive detectors. In a strange twist of physics history, these researchers didn’t associate their work with entanglement per se, let alone with Einstein’s puzzlement over the phenomenon. Several years after the fact, theorists David Bohm and Yakir Aharonov realized that the experiments had breathed life into the famous EPR thought experiment of Einstein, Boris Podolsky, and Nathan Rosen.
Today, physics students at Caltech, the University of Edinburgh, and elsewhere routinely perform the Wu-Shaknov experiment. But what about the rest of us who lack the resources of such august institutions? With the encouragement of David Prutchi, who practically invented the category of amateur quantum physicist, I decided to try to recreate the Bleuler-Bradt experiment in my basement workshop.
The parts I use are:
- two Aware RM-60 Geiger counters
- di
