We present an improved phase estimation scheme employing entangled coherent states and demon- strate that the states give the smallest variance in the phase parameter in comparison to NOON, BAT and "optimal" states under perfect and lossy conditions. As these advantages emerge for very modest particle numbers, the optical version of entangled coherent state metrology is achievable with current technology.
@article{arxiv.1101.5044,
title = {Quantum metrology with entangled coherent states},
author = {Jaewoo Joo and William J. Munro and Timothy P. Spiller},
journal= {arXiv preprint arXiv:1101.5044},
year = {2011}
}