On the description of multiple measurements of an unstable state

Miloslav Havlíček, Pavel Exner

Mikhail Aleksandrovich Braun, K. Urbanowski

Darren Cudd

This note addresses the outcome problem in quantum measurement by identifying outcome singularity as a physical stability condition rather than a probabilistic or observer-driven event. It argues that once quantum coherence is lost, a description containing multiple simultaneous classical outcomes is physically unrealizable because it violates fundamental requirements of classical consistency, information stability, and thermodynamic irreversibility. Drawing on principles from information theory and dynamical systems, the note shows that a single, definite outcome emerges as the only dynamically stable attractor state, while outcome multiplicity represents an unstable, coordination-intensive configuration that cannot persist in a classical regime. No collapse postulate, observer assumption, or modification of quantum mechanics is introduced.

Pavel Exner

S.G. Matinyan, Mark E. Perel’man

Francesco Giacosa

After reviewing the description of an unstable state in the framework of Lee Hamiltonians (valid both for Quantum Mechanics (QM) and Quantum Field Theory (QFT)), we consider some theoretical aspects of non-exponential decays: the case of two decay channels, the broadening of the energy spectrum at short times, the effect of an imperfect measurement, the link to QFT, and the decay of an unstable moving particle with definite momentum. All the presented effects were not confirmed in experiments, hence are at the present stage predictions.