Exceptional points in non-Markovian quantum-state diffusion: From coefficient dynamics to state signatures

arXiv:2611.13221v1 Announce Type: new Abstract: An exceptional point of a memory-coefficient equation need not have the same signature in every quantum-state observable. We examine this relation within exact non-Markovian quantum-state diffusion (NMQSD), following the same operator closure from its coefficient dynamics to the non-Markovian master equation obtained by noise averaging. A finite homogeneous lift identifies the Jordan chains reached by the causal initialization, while state reconstruction determines which contributions survive in a specified readout. Two models expose the distinction. For common-bath qubits restricted to zero and one excitation, a noise-independent lowering-form $O$ operator gives a closed master equation.