Coherent States

Coherent states (of the harmonic oscillator) were introduced by Erwin Schrödinger (1887-1961) at the very beginning of quantum mechanics in response to a complaint by Lorentz that Schrödinger’s wave functions did not display classical motion. Schrödinger obtained solutions that were Gaussians having the width of the ground state. The expectation values of the coordinate and momentum for these Gaussian solutions oscillate in time in just the same way as the coordinate and momentum in the classical theory of the harmonic oscillator. In modern parlance Schrödinger’s solutions are the 2-parameter (〈x〉, 〈p〉) states