Exponentially enhanced quantum metrology.
We show that when a suitable entanglement-generating unitary operator depending on a parameter is applied on N qubits in parallel, a precision of the order of 2(-N) in estimating the parameter may be achieved. This exponentially improves the precision achievable in classical and in quantum nonentangling strategies.
Roy
S M
SM
Computer Science, University of York, York YO 10 5DD, United Kingdom.
Braunstein
Samuel L
SL