Sub shot-noise interferometric phase sensitivity with beryllium ions Schrödinger cat statesL. Pezzé and A. Smerzi
CNR-INFM BEC Center and Dipartimento di Fisica - Università di Trento, I-38050 Povo, Italy
received 20 November 2006; accepted in final form 19 March 2007; published May 2007
published online 27 April 2007
Interferometry with NOON quantum states can provide unbiased phase estimation with a sensitivity scaling as given a prior knowledge that the true phase shift lies in the interval . The protocol requires a total of NT=2p-1 particles (unequally) distributed among p independent measurements and overcomes basic difficulties present in previously proposed approaches. We demonstrate the possibility to obtain a phase sensitivity beating the classical shot-noise limit using published probabilities retrieved experimentally for the creation of Schrödinger cat quantum states containing up to N=6 beryllium ions.
03.75.Dg - Atom and neutron interferometry.
03.65.Ud - Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.).
42.50.-p - Quantum optics.
© Europhysics Letters Association 2007