INFORMATION ENTROPY AND SQUEEZING OF QUANTUM FLUCTUATIONS

Quantum-mechanical entropies of position and momentum operators in a g iven state are shown to be reasonable and sensitive measures for squee zing of quantum fluctuations. It is shown to be true not only for stat es having Gaussian wave functions but also for more general, both pure and mixed, quantum states. A simple proof that the squeezing exhibite d by the variance is always accompanied by a corresponding entropy red uction below the entropy vacuum level is given. These results show tha t the information entropy is not only a theoretically satisfactory con cept but can also be useful as a tool for more practical quantum-optic s applications.