HEISENBERG-PICTURE APPROACH TO THE EXACT QUANTUM MOTION OF A TIME-DEPENDENT HARMONIC-OSCILLATOR

The generalized invariant and the exact quantum motions are found in the Heisenberg picture for a harmonic oscillator with time-dependent mass and frequency in terms of classical solutions. It is shown that the Heisenberg pictures gives a relatively simpler picture that the Schrödinger picture and also manifestly exhibits the time independency of the invariant. We apply this method to the system with a linear sweep of frequency and Paul trap and study the squeezing properties. © 1995 The American Physical Society.