A good physics undergrad could assemble this and demonstrate it successfully in a day. It's really a Mach Zender interferometer (https://en.wikipedia.org/wiki/Mach%E2%80%93Zehnder_interfero...) which is one of the nicest designs for doing quantum information experiments.
The laser they use isn't anything super-special, although it isn't like what you'd get if you bought a laser pointer or a cheap laser engraver. The beam size is very fine and the beam shape is round. Most of the other parts are fairly generic but precisely made. The most exciting part is the beamsplitters, https://en.wikipedia.org/wiki/Beam_splitter since they are key to assembling the interferometer itself.
Even so, an effect that can be demonstrated with tabletop equipment in a lab seems more intuitively real to me than something that requires a giant particle accelerator...
100 or 200 years ago a more or less average person could set up cutting-edge scientific experiments with basic equipment and patient observation – this was the modus operandi of Michael Faraday[1] for example. Sadly it seems like those days are mostly behind us now.
My friend did the experiment in an afternoon Physics lab (princeton), almost all of of this is due to innovations in precision manufacturing and material science.