Lossy quantum-optical metrology with squeezed states

We study the precise phase estimation using squeezed states in the presence of photon loss. Our exact quantum Fisher information calculation shows significant enhancement even though the loss is very large and sets a benchmark for experimental realization. We show that if we blindly use the existing parity measurement scheme [Anisimov et al., Phys. Rev. Lett. 104, 103602 (2010)] for the ideal case, the result will be even worse than the classical case given very small loss. Using our formulas, we can optimize the measurement result by making loss-dependent phase shift and choosing appropriate squeezed states (average photon number of squeezed states).