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Durkin, Gabriel A

Publications and source records attributed to Durkin, Gabriel A.

3 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2011

Scaling laws for precision in quantum interferometry and the bifurcation landscape of the optimal state

Phase precision in optimal two-channel quantum interferometry is studied in the limit of large photon number N>>1, for losses occurring in either one or both channels. For losses in one channel an optimal state undergoes an intriguing sequence of local bifurcations as the number of photons (or losses) increase. The optimal state has a continuous form in the Fock state basis for large N. The loss parameter limits any precision improvement over classical light to at most a constant factor independent of N. We determine a crossover value of photon number N{sub c} beyond which supraclassical precision is progressively lost.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2010

Parameter Estimation with Entangled Photons Produced by Parametric Down-Conversion

We explore the advantages offered by twin light beams produced in parametric down-conversion for precision measurement. The symmetry of these bipartite quantum states, even under losses, suggests that monitoring correlations between the divergent beams permits a high-precision inference of any symmetry-breaking effect, e.g., fiber birefringence. We show that the quantity of entanglement is not the key feature for such an instrument. In a lossless setting, scaling of precision at the ultimate ''Heisenberg'' limit is possible with photon counting alone. Even as photon losses approach 100% the precision is shot-noise limited, and we identify the crossover point between quantum and classical precision as a function of detected flux. The predicted hypersensitivity is demonstrated with a Bayesian simulation.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗