Abstract
The complex amplitude of a harmonic oscillator is constant in the absence of driving forces. Although the uncertainty principle forbids precise measurements of and simultaneously (), alone can be measured precisely and continuously ("quantum nondemolition measurement"). Examples are given of measuring systems that do this job. Such systems might play a crucial role in gravitational-wave detection and elsewhere.
- Received 23 January 1978
DOI:https://doi.org/10.1103/PhysRevLett.40.667
©1978 American Physical Society