Useful Multiparticle Entanglement and Sub-Shot-Noise Sensitivity in Experimental Phase Estimation

Year: 2011

Authors: Krischek R., Schwemmer C., Wieczorek W., Weinfurter H., Hyllus P., Pezzè L., Smerzi A.

Autors Affiliation: Fakultat fur Physik, Ludwig-Maximilians Universitat Munchen, D-80799 Munchen, Germany; Max-Planck Institut fur Quantenoptik, Hans-Kopfermann Strasse 1, D-85748 Garching, Germany; INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy; Laboratoire Charles Fabry UMR 8501, Institut d’Optique, CNRS, Université Paris Sud 11, 2 Avenue Fresnel, 91127 Palaiseau cedex, France

Abstract: We experimentally demonstrate a general criterion to identify entangled states useful for the estimation of an unknown phase shift with a sensitivity higher than the shot-noise limit. We show how to exploit this entanglement on the examples of a maximum likelihood as well as of a Bayesian phase estimation protocol. Using an entangled four-photon state we achieve a phase sensitivity clearly beyond the shot-noise limit. Our detailed comparison of methods and quantum states for entanglement enhanced metrology reveals the connection between multiparticle entanglement and sub-shot-noise uncertainty, both in a frequentist and in a Bayesian phase estimation setting.

Journal/Review: PHYSICAL REVIEW LETTERS

Volume: 107 (8)      Pages from: 80504-1  to: 80504-5

More Information: We thank N. Kiesel, W. Laskowski, and O. Guhne for stimulating discussions. R.K., C.S., W.W., and H.W. acknowledge the support of the DFG-Cluster of Excellence MAP, the EU projects QAP and Q-Essence, and the DAAD/MNISW exchange program. W.W. and C. S. thank QCCC of the Elite Network of Bavaria and P.H. thanks the ERC Starting Grant GEDENTQOPT.
KeyWords: Estimation; Maximum likelihood estimation; Spurious signal noise
DOI: 10.1103/PhysRevLett.107.080504

Citations: 96
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