Abstract
We find the optimal scheme for quantum phase estimation in the presence of loss when no a priori knowledge on the estimated phase is available. We prove analytically an explicit lower bound on estimation uncertainty, which shows that, as a function of the number of probes, quantum precision enhancement amounts at most to a constant factor improvement over classical strategies.
- Received 21 June 2010
DOI:https://doi.org/10.1103/PhysRevA.82.053804
©2010 American Physical Society