Quantum metrology

Phys Rev Lett. 2006 Jan 13;96(1):010401. doi: 10.1103/PhysRevLett.96.010401. Epub 2006 Jan 3.


We point out a general framework that encompasses most cases in which quantum effects enable an increase in precision when estimating a parameter (quantum metrology). The typical quantum precision enhancement is of the order of the square root of the number of times the system is sampled. We prove that this is optimal, and we point out the different strategies (classical and quantum) that permit one to attain this bound.