  The inability of Schrodinger's unitary time evolution to describe measurement
of a quantum state remains a central foundational problem. It was recently
suggested that the unitarity of Schrodinger dynamics can be spontaneously
broken, resulting in measurement as an emergent phenomenon in the thermodynamic
limit. Here, we introduce a family of models for spontaneous unitarity
violation that apply to generic initial superpositions over arbitrarily many
states, using either single or multiple state-independent stochastic
components. Crucially, we show that Born's probability rule emerges
spontaneously in all cases.
