Time evolution of an unstable quantum system

TL;DR

This paper reviews theoretical aspects of unstable quantum systems, including non-exponential decay effects and their implications, providing predictions that await experimental confirmation.

Contribution

It offers a comprehensive theoretical analysis of unstable quantum states, covering multiple decay phenomena and their connections to quantum field theory.

Findings

Predicted non-exponential decay effects in quantum systems

Analyzed the impact of measurement imperfections on decay

Linked decay phenomena to quantum field theory principles

Abstract

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.