Abstract

The precision in any parameter estimation is limited by the quantum nature of whatever probing system is used. In the simplest case of N independent systems probing a parameter ϕ, the precision is limited by the shot-noise, δϕ∝1/√N. Quantum correlated probes (such as squeezed or entangled states) have been demonstrated to be useful for improving the sensitivity of a broad class of measurements (interferometry, magnetometry, imaging, etc.) with the uncertainty that scales as 1/N, scaling law known as Heisenberg limit. It has been recently proposed [1] that dynamics in which probes are coupled non-linearly to the parameter being estimated can beat the Heisenberg limit (e. g. if k-th power of a probe operator appears in the Hamiltonian, it leads to δϕ scaling as 1/N^k-1/2 without any use of entanglement). In a polarization-based atom-light interface, a Hamiltonian nonlinear in the Stokes operators can be produced using optical nonlinearities. Here we investigate application to precision measurements with better-than-Heisenberg scaling.

© 2009 IEEE