Physics – Quantum Physics
Scientific paper
2008-11-20
Phys. Rev. A 79, 033834 (2009)
Physics
Quantum Physics
typos corrected
Scientific paper
10.1103/PhysRevA.79.033834
We give the optimal bounds on the phase-estimation precision for mixed Gaussian states in the single-copy and many-copy regimes. Specifically, we focus on displaced thermal and squeezed thermal states. We find that while for displaced thermal states an increase in temperature reduces the estimation fidelity, for squeezed thermal states a larger temperature can enhance the estimation fidelity. The many-copy optimal bounds are compared with the minimum variance achieved by three important single-shot measurement strategies. We show that the single-copy canonical phase measurement does not always attain the optimal bounds in the many-copy scenario. Adaptive homodyning schemes do attain the bounds for displaced thermal states, but for squeezed states they yield fidelities that are insensitive to temperature variations and are, therefore, sub-optimal. Finally, we find that heterodyne measurements perform very poorly for pure states but can attain the optimal bounds for sufficiently mixed states. We apply our results to investigate the influence of losses in an optical metrology experiment. In the presence of losses squeezed states cease to provide Heisenberg limited precision and their performance is close to that of coherent states with the same mean photon number.
Aspachs Mariona
Bagan Emili
Calsamiglia John
Munoz-Tapia Ramon
No associations
LandOfFree
Phase estimation for thermal Gaussian states does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Phase estimation for thermal Gaussian states, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Phase estimation for thermal Gaussian states will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-162359