Abstract
The optimal precision of frequency measurements in the presence of decoherence is discussed. We analyze different preparations of two-level systems as well as different measurement procedures. We show that standard Ramsey spectroscopy on uncorrelated atoms and optimal measurements on maximally entangled states provide the same resolution. The best resolution is achieved using partially entangled preparations with a high degree of symmetry.
- Received 7 July 1997
DOI:https://doi.org/10.1103/PhysRevLett.79.3865
©1997 American Physical Society