Unraveling Dicke Superradiant Decay with Separable Coherent Spin States

We show that Dicke superradiant decay from a fully inverted state can at all times be described by a positive statistical mixture of coherent spin states (CSS). Since CSS are separable, this implies that no entanglement is involved in Dicke decay. Based on this result, we introduce a new numerical quantum trajectory approach leading to low-entanglement unravelings. This opens up possibilities for large-scale numerical simulations of collective decay processes.