The Entangled spin ½ particle pairs versus hidden variables simulation allows students to assess whether a simple hidden variable theory would agree with measurement outcomes predicted by quantum theory. The simulation shows a source of particle pairs in the middle of two Stern-Gerlach apparatuses (SGAs), that can each individually be oriented at three axes at 120 degrees to one another. The observers measure outcomes of + or – (depicted as flashes on screens) irrespective of orientation depending on whether the deflection is positive or negative along the measurement axis. When the main controls are set to “Quantum theory”, the particles pairs are entangled and always give opposite results when both SGAs have the same orientation. When the main controls are set to “Hidden variable theory”, the particles have pre-determined definite measurement outcomes defined by instruction sets, which also give opposite results whenever both SGAs have the same orientation. An accompanying activity for this simulation is available at http://quantumphysics.iop.org and at www.st-andrews.ac.uk/physics/quvis. The simulation can be downloaded from the QuVis website www.st-andrews.ac.uk/physics/quvis.
This simulation is part of the UK Institute of Physics New Quantum Curriculum, see http://quantumphysics.iop.org. Simulations and accompanying activities can be accessed from the IOP site and from www.st-andrews.ac.uk/physics/quvis. Sharing of these resources is encouraged, with all usage under the Creative Commons CC BY-NC-ND licence. Instructors can email firstname.lastname@example.org for activity solutions and to request to modify materials.