We Share Science

Many-particle interference beyond many-boson and many-fermion statistics

Video abstract for the article 'Many-particle interference beyond many-boson and many-fermion statistics' by Malte C Tichy, Markus Tiersch, Florian Mintert and Andreas Buchleitner (Malte C Tichy et al 2012 New J. Phys. 14 093015). Read the full article in New Journal of Physics at http://iopscience.iop.org/1367-2630/14/9/093015/article. GENERAL SCIENTIFIC SUMMARY Introduction and background. All elementary particles belong to one of two fundamentally different species: bosons and fermions. Bosons tend to multiply populate single-particle quantum states; however, this is impossible for fermions due to the Pauli principle. This quantum statistical behavior is well established, e.g. for incoherently prepared cold gases and thermal photons. Today, one can also observe the fermionic and bosonic behavior of particles that are coherently prepared in pure Fock-states: beam-splitter-like devices can be used to super-impose particles that originate from different initial modes, and the number of particles in the output modes can be counted reliably. In contrast to the well-known incoherent statistical behavior, sharp interference effects now dominate the picture. Main results. Generalizing previous few-particle interference schemes to the scattering of many bosons and many fermions on a Fourier multimode beam splitter, we theoretically derive a law that predicts the strict suppression of scattering events due to destructive interference. Surprisingly, bosons and fermions do not always show an opposed behavior—as they usually do in incoherent environments—but they often exhibit the very same fully suppressed events. Only when the coherence of the initial state is jeopardized does an average bosonic or fermionic behavior emerge and thereby recovers the familiar statistical behavior. Wider implications. Our results provide a simple recipe to characterize the indistinguishability and the many-particle coherence of many-boson and many-fermion states in the experiment. The strong interference signatures that we found thus benchmark many-particle decoherence processes and assess the quality of photonic entanglement that is generated with multimode beam splitters.