Quantum Estimation of Kerr Nonlinearity in Driven-Dissipative Systems

Isamu Ohnishi

Dong Xie, Chunling Xu, An Min Wang

We mainly investigate the quantum measurement of Kerr nonlinearity in the driven-dissipative system. Without the dissipation, the measurement precision of the nonlinearity parameter χ scales as “super-Heisenberg scaling” 1/N2 with N being the total average number of particles (photons) due to the nonlinear generator. Here, we find that “super-Heisenberg scaling” 1/N3/2 can also be obtained by choosing a proper interrogation time. In the steady state, the “super-Heisenberg scaling” 1/N3/2 can only be achieved when the nonlinearity parameter is close to 0 in the case of the single-photon loss and the one-photon driving or the two-photon driving. The “super-Heisenberg scaling” disappears with the increase of the strength of the nonlinearity. When the system suffers from the two-photon loss in addition to the single-photon loss, the optimal measurement precision will not appear at the nonlinearity χ=0 in the case of the one-photon driving. Counterintuitively, in the case of the two-photon driving we find that it is not the case that the higher the two-photon loss, the lower the measurement precision. It means that the measurement precision of χ can be improved to some extent by increasing the two-photon loss.

Daniel F. Walls, Gerard J Milburn

Ulrich Weiß

Muhammad Asjad, Berihu Teklu, Matteo G. A. Paris

We address multiparameter quantum estimation for coherently driven nonlinear Kerr resonators in the presence of loss. In particular, we consider the realistic situation in which the parameters of interest are the loss rate and the nonlinear coupling, whereas the amplitude of the coherent driving is known and externally tunable. Our results show that this driven-dissipative model is asymptotically classical, i.e., the Uhlmann curvature vanishes, and the two parameters may be jointly estimated without any additional noise of quantum origin. We also find that the ultimate bound to precision, as quantified by the quantum Fisher information (QFI), increases with the interaction time and the driving amplitude for both parameters. Finally, we investigate the performance of quadrature detection, and show that for both parameters the Fisher information oscillates in time, repeatedly approaching the corresponding QFI.

Neeraj Singh, Raj Kumar, Ajay Wasan