Physical Review A
Nonadiabatic geometric phase in periodic linear systems
Y. C. Ge, Mark Sheard Child
Abstract
The method used by Garrison and Wright for the calculation of complex geometrical phases in quantal dissipative systems is extended to all time periodic linear systems, including classical linear systems with nonunitary time evolution. Each eigenvector $|{x}_{i}(t)〉$ of the period map modified by a complex scaling exponent ${\ensuremath{\theta}}_{i}(t)$ has an associated complex geometrical phase, which admits a solid angle interpretation in two-dimensional systems. Pairs of the $|{x}_{i}(t)〉$ commonly determine quadratic periodic invariants corresponding to topologically distinct surfaces of the invariant torus, and a connection between the scaling exponents and classical angle variables is established. The method is illustrated by the calculation of explicit expressions for the classical and quantal nonadiabatic phases associated with angular momentum precession. A second application to a general quadratic Hamiltonian extends existing adiabatic results to the classical and quantal nonadiabatic phases of both elliptic and hyberbolic systems. The relevance of torus ensemble averaging in a classical angle-action formulation is discussed.