Proposal for demonstrating the Hong–Ou–Mandel effect with matter waves

The Hong–Ou–Mandel effect is a demonstration of destructive quantum interference between pairs of indistinguishable bosons, realised so far only with massless photons. Here we propose an experiment to realize this effect in the matter-wave regime using pair-correlated atoms produced via a collision of two Bose–Einstein condensates and subjected to two laser-induced Bragg pulses. We formulate a measurement protocol for the multimode matter-wave field, which—unlike the typical two-mode optical case—bypasses the need for repeated measurements under different displacement settings of the beam splitter, markedly reducing the number of experimental runs required to map out the interference visibility. Although the protocol can be used in related matter-wave schemes, we focus on condensate collisions. By simulating the entire experiment, we predict a Hong–Ou–Mandel dip visibility of ~69%. This visibility highlights strong quantum correlations between the atoms, paving the way for a possible demonstration of a Bell inequality violation with massive particles in a related Rarity–Tapster setup. The Hong–Ou–Mandel effect is a well-known demonstration of quantum interference phenomena between pairs of indistinguishable bosons, yet it has only been seen with massless photons. Here, the authors propose an approach to realize this effect for matter waves using two colliding Bose–Einstein condensates.