Method of allowing for dissipative effects in quantum nonlinear optical processes

Peter Goetsch, Robert Graham

Abstract The stochastic Schrödinger equation, a novel method for describing the dissipative dynamics of open quantum systems interacting with their environment, is applied to some nonlinear optical processes, namely nonlinear absorption and second‐harmonic generation, the latter also in the range of instabilities and classical chaotic behaviour. Where possible the results are compared with numerical simulations of the positive P representation, which in some cases are found to give unreliable results.

Yu Yang, Igor Kladarić, Maxwell Drimmer +6 more

Strong nonlinear interactions between quantized excitations are an important resource for quantum technologies based on bosonic oscillator modes. However, most electromagnetic and mechanical nonlinearities arising from intrinsic material properties are far too weak compared to dissipation in the system to allow for nonlinear effects to be observed on the single-quantum level. To overcome this limitation, electromagnetic resonators in both the optical and microwave frequency regimes have been coupled to other strongly nonlinear quantum systems such as atoms and superconducting qubits, allowing for the demonstration of effects such as photon blockade and coherent quantum protocols using the Kerr effect. Here, we demonstrate the realization of the single-phonon nonlinear regime in a solid-state mechanical system. The single-phonon anharmonicity in our system exceeds the decoherence rate by a factor of 6.8, allowing us to use the lowest two energy levels of the resonator as a mechanical qubit, for which we show initialization, readout, and a complete set of direct single qubit gates. Our work adds another unique capability to a powerful quantum acoustics platform for quantum simulations, sensing, and information processing.

R. Loudon

Daniel F. Walls, Gerard J Milburn

A. V. Prokhorov, Mikhail Yu. Gubin, A. Yu. Leksin +3 more

The problem of nonlinear scattering of optical pulses in a dense three-level atomic medium with continuous pumping is considered with allowance for the local field effects. The physical requirements on the parameters of the medium and field are formulated, and the ranges of these parameters for which stationary solitons are effectively formed in the model of a quartz waveguide doped with 87 Rb atoms are determined using variational methods. It is found that disregarding the local field in this model results in violation of soliton stability in the predicted parameter range.