Abstract

In the short review of the achieved sensitivity in the quantum-non-demolition measurements the best results were obtained in the measurements of the energy of in optical band in e.m. resonators and in traveling e.m. waves on the basis of cubic nonlinearities of the e.m. systems. In both cases the standard quantum limit was crossed. There are good prospects from the point of view of existing technology for the QND measurements of the speed of a free mass and of quadrature amplitude of a mechanical resonator, also there are good prospects for the counting without absorption of microwave quanta in superconductive e.m. resonators. The analysis of the deflection scheme of QND measurements show that in optical band the resolution of the energy of a single optical quantum in QND measurements may be better than 10"(-1) of the energy of the quantum. The list of nonsolved problems is presented as well as possible applications of QND methods for fundamental physical problems.

© 1994 Optical Society of America