Number 82 (Story #1), June 2, 1992 by Phillip F. Schewe and Ben Stein SQUEEZED LIGHT has been used in the spectroscopic study of atomic cesium (E.S. Polzik et al., Phys. Rev. Lett. 18 May 1992). Quantum mechanics holds that a beam of light, even laser light, exhibits small energy irregularities (shot noise) owing to the effects of vacuum fluctuations (electromagnetic fields in the vacuum whose omnipresence is sanctioned by Heisenberg's uncertainty principle). Over the past decade physicists have been able partially to overcome this problem by reducing the noise in either the phase or the amplitude of the light at the expense of the other. The resultant "squeezed light," or at least that component of the light with a noise level lower than normally allowed by the uncertainty principle, is of interest, both in its own right, representing as it does a specimen of "nonclassical light," and as a potential high-precision probe of atomic physics. Scientists at Caltech (H. Jeffrey Kimble, 818-356-8340) have used a tunable beam of squeezed light over a wavelength range of 840-970 nm to measure, with half the usual noise, certain atomic transitions in cesium. (Science News, 30 May 1992.)