Quantum dynamics in Weyl-Heisenberg coherent states Artur Miroszewski
[email protected] National Centre for Nuclear Research Ludwika Pasteura 7, 02-093, Warsaw, Poland Abstract The article explores a new formalism for describing motion in quantum mechanics. The con- struction is based on generalized coherent states with evolving fiducial vector. Weyl-Heisenberg coherent states are utilised to split quantum systems into ‘classical’ and ‘quantum’ degrees of freedom. The decomposition is found to be equivalent to quantum mechanics perceived from a semi-classical frame. The split allows for introduction of a new definition of classical state and is a convenient starting point for approximate analysis of quantum dynamics. An example of a meta-stable state is given as a practical illustration of the introduced concepts. 1 Introduction Coherent states have occupied physicists and mathematicians for almost a century. First introduced in 1926 by Edwin Schr¨odinger[1] in their standard formulation and studied by John von Neumann [2] from the phase space perspective they were forgotten until beginning of the 1960s. Recognizing their usefulness in the subject of atomic optics [3, 4], introduction of the concept of generalized coherent states [5–7] and their connection to group theory [8] resulted in unflagging interest in coherent states until today. Their success in the physical sciences can be seen from the perspective of the amount of fields which employed coherent states as an effective tool. Among others, superfluidity [9], superra- diance [10, 11], quantum electrodynamics [12–14], solitons [15–17], statistical physics and semiclassical limits [18, 19], scattering processes [20] and recently quantum cosmology [21–23].