On Complete Orthonormal Sets of Coherent and of Squeezed States

A complete set of harmonic oscillator orthogonal coherent states is discussed. The properties of the states are studied, in particular towards applications as a basis for nonstationary problems. To make such a basis even more flexible, an orthonormal set of squeezed states is introduced. These states share most of the properties that make the familiar coherent states useful in applications. They are also extremal states of the uncertainty product. Their particular advantage, beyond the obvious one of orthogonality, is in applications to the dynamics of excited states.