  The stochastic nature of quantum mechanics is more naturally reflected in a
bilinear two-process representation of density matrices rather than in squared
wave functions. This proposition comes with a remarkable change of the
entanglement mechanism: entanglement effects do not originate from
superpositions of wave functions, but result from the bilinear structure of
density matrices. Quantum interference appears as a multiplicative phenomenon
rather than an additive superposition mechanism. We propose two general
requirements such that the bilinear representation of density matrices is given
in terms of two uniquely defined, identically distributed, Markovian stochastic
jump processes. These general ideas are illustrated for the
Einstein-Podolsky-Rosen and double-slit experiments. The expression of the
stochastic nature of quantum mechanics in terms of random variables rather than
their probability distributions facilitates an ontological viewpoint and leads
us to a bra-ket interpretation of quantum mechanics.
