Higher-order interference between multiple quantum particles interacting nonlinearly

The double-slit experiment is the most direct demonstration of interference between individual quantum objects. Since similar experiments with single particles and more slits produce fringes reducible to a combination patterns it usually argued that occurs pairs trajectories, compactly denoted as second-order interference. Here we show mechanics in fact allows for arbitrarily high order. This naturally when one considers multiple objects interacting presence nonlinearity, both which are required observe higher-order We make this clear by treating generalised multi-slit interferometer using second-quantisation. then present explicit experimentally-relevant examples photons nonlinear media an interfering Bose-Einstein condensate particle-particle interactions. These all perfectly described theory, yet exhibit based on nonlinearly.