Statistical properties and quantum nature of light in optical cavities combining second- and third-order nonlinearities

Squeezing is a typical quantum effect arising in nonlinear systems and is relevant for quantum computers and other applications. We investigate a scheme consisting of an optical cavity containing a pair of connected quantum wells through electronic tunneling. Nonlinear excitonic interactions in the direct and indirect exciton fields are considered. Furthermore, the cavity interacts with an optical parametric oscillator, injecting squeezed photons into the cavity.

The external squeezed source increases the excitonic density. By solving the quantum Langevin equations in the frequency domain and determining the noise spectrum of transmitted light, we found that indirect exciton nonlinearity produces stronger squeezing than direct exciton nonlinearity. In all scenarios, incorporating the parametric oscillator can substantially raise the degree of squeezing.

The impact of the second-order nonlinearity is much more noticeable in the weak coupling regime compared to excitonic nonlinearity. Nevertheless, the nonlinearity describing the exciton produces higher squeezing than the optical parametric oscillator in the strong coupling regime. It is worth noting that the squeezing effect manifests a high resistance and stability against the bath temperature, essentially in the weak coupling regime. The proposed system may have potential applications since it significantly reduces noise for a specific frequency range in a single and compact device.