Quantum Metrology: Dynamics versus Entanglement

Animesh Datta
Matthew J. Davis
Steven T. Flammia
Anil Shaji
Carlton M. Caves
Physical Review Letters, 101(2008), pp. 040403-4

Abstract

A parameter whose coupling to a quantum probe of n constituents includes all two-body interactions between the constituents can be measured with an uncertainty that scales as 1/n to the 3/2, even when the constituents are initially unentangled. We devise a protocol that achieves the 1/n to the 3/2 scaling without generating any entanglement among the constituents, and we suggest that the protocol might be implemented in a two-component Bose-Einstein condensate.

Research Areas