Quantum Interferometry at the Heisenberg Limit

Hwang Lee, Yang Gao

Hermann Uys, Pierre Meystre

The phase sensitivity of interferometers is limited by the so-called Heisenberg limit, which states that the optimum phase sensitivity is inversely proportional to the number of interfering particles $N$, a $1∕\sqrt{N}$ improvement over the standard quantum limit. We have used simulated annealing, a global optimization strategy, to systematically search for quantum interferometer input states that approach the Heisenberg-limited uncertainty in estimates of the interferometer phase shift. We compare the performance of these states to that of other nonclassical states already known to yield Heisenberg-limited uncertainty.

Miller Eaton, Rajveer Nehra, Aye Win +1 more

We propose a Heisenberg-limited quantum interferometer whose input is twin optical beams from which one or more photons have been indistinguishably subtracted. Such an interferometer can yield Heisenberg-limited performance while at the same time giving a direct fringe reading, unlike for the twin-beam input of the Holland-Burnett interferometer. We propose a feasible experimental realization using a photon-number correlated source, such as nondegenerate parametric down-conversion, and perform realistic analyses of performance in the presence of loss and detector inefficiency.

Alfredo Luis, Luis Lorenzo Sánchez-Soto

Christopher C. Gerry, Adil Benmoussa

We discuss the generation of two mode maximally entangled coherent states using a weak nonlinear medium. We then discuss their applications to quantum metrology (Heisenberg-limited interferometry), quantum lithography, and violations of Bell-type inequalities.