Entanglement and Sensitivity in Precision Measurements with States of a Fluctuating Number of Particles

Philipp Hyllus (1) , Luca Pezzé (2) , Augusto Smerzi (1)

1 INO-CNR BEC Center and Dipartimento di Fisica
2 laboratoire Charles Fabry de l'Institut d'Optique / Optique atomique

The concepts of separability, entanglement, spin squeezing, and the Heisenberg limit are central in the theory of quantum-enhanced metrology. In the current literature, these are well established only in the case of linear interferometers operating with input quantum states of a known fixed number of particles. This manuscript generalizes these concepts and extends the quantum phase estimation theory by taking into account classical and quantum fluctuations of the particle number. Our analysis concerns most of the current experiments on precision measurements where the number of particles is known only on average

Domains: Physics [physics]; Physics [physics]; Optics [physics.optics]

Philipp Hyllus, Luca Pezzé, Augusto Smerzi. Entanglement and Sensitivity in Precision Measurements with States of a Fluctuating Number of Particles. Physical Review Letters, 2010, 105 (12), pp.120501. ⟨10.1103/PhysRevLett.105.120501⟩. ⟨hal-00746823⟩