Abstract

With a proper choice of the initial wave function it is possible to obtain reduced or squeezed quantum fluctuations of the un- certainty of the position operator for a free particle.¹ Such an effect is important for the so-called quantum nondemolition measurements of weak external signals. We show that for both free-motion and harmonic oscillation such a property holds owing to the conformal invariance of the Schrödinger equation. We show that for harmonic oscillation it is possible to reduce the quantum fluctuations of the measured photon below the standard quantum limit.² Possible applications to optical communications and weak signal detections are also presented

© 1984 Optical Society of America