Abstract

In common interference effects the intensity distribution does not depend on the quantum nature of the interfering particles. For example, you get the same interference pattern in a double slit experiment with photons (bosons) as with neutrons (fermions) of the same wavelength. If, however, you overlap two identical particles at a beamsplitter the resulting second order interference effect will depend on the kind of particles. While photons (symmetric wavefunction) always leave the beamsplitter in the same output¹, two fermions (anti-symmetric wavefunction) will end in different outputs because they never can be in identical quantum states. Thus, placing detectors in each of the outputs of the beamsplitter, one observes a decrease in the coincidence probability for bosons but an increasing coincidence probability for fermions, relative to the classical coincidence probability for independent particles. As long as we do not have a source for correlated fermion pairs an experiment with fermions cannot be carried out.

© 1998 IEEE