A Do-It-Yourself Quantum Eraser: What you will need for the experiment

  • A very dark room.
  • Polarizing film. Plain gray, high-quality film ("experimental grade") gives the best results; avoid film tinted with a color (see this page for some places that sell film). You need to cut it into six squares, each about two inches on a side. The box on page 94 describes what polarizers do to photons.
  • A laser, such as a laser pointer. If yours emits polarized light, align its polarization at 45 degrees from the vertical. If your laser is not polarized, include a polarizer at 45 degrees immediately after the laser at every step. Use a rubber band to keep the laser turned on.
  • A thin, straight piece of wire, such as from an unused twist tie or a straightened staple. The thinner the better.
  • Some tinfoil and a pin to poke a hole in it. The light that goes through the pinhole will expand outward, forming a narrow, conical beam. The pinhole makes the patterns dimmer but may improve the results if the room is dark enough.
  • Some stands to hold the laser and polarizers in place. These could be as low-tech as cereal boxes.
  • A screen to display the final patterns. The bare wall will do if it is plain enough; otherwise use a sheet of paper.
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