Towards deterministic non-Gaussianity on a chip

Abstract

We propose cascaded spontaneous four-wave mixing (SFWM) in microring resonators as a scalable and efficient approach for directly generating non-Gaussian states of light. Focusing on the well-understood "low-gain" regime, we demonstrate that triplet generation through cascaded SFWM can be achieved with high efficiency and favorable spectral characteristics using realistic microring sources in AlGaAs. The ability to achieve the generation of light in a single set of supermodes -- and the accessibility of the "high-gain" regime at realistic pump powers -- makes this source a promising candidate as a direct and deterministic source of non-Gaussian light for photonic quantum information processing.

Figures (4)

• Figure 1: a) Subsequent microring resonators coupled to a bus waveguide, each coupled to a phantom waveguide to model photon losses. b) Electric field ($E_x$) mode profile of the TE$_{00}$ mode. Mode simulations are done in Lumerical with a bend radius of 10 $\mu\mathrm{m}$, using the refractive index for Al$_{0.3}$Ga$_{0.7}$As from bib:Adachi1985.
• Figure 2: Energy diagrams for the generation of non-degenerate triplets (a), and degenerate triplets (b). The SFWM process for the first (second) ring is given in each subfigure's top (bottom) panel.
• Figure 3: Visualization of the total triphoton wavefunction $|\Psi|^2\equiv|\Psi^{\mathrm{ac,ac,ac}}(k_1,k_2,k_3;t\rightarrow\infty)|^2$ for configuration $A$ (a), $B$ (b) and $C$ (c); we use $x_i = v_{S_i}(k_i-K_{S_i})/\bar{\Gamma}_{S_i}$, where $K_{S_i}$ indicates the reference wavenumber for the $i^{th}$ signal, and in the panel perpendicular to the $x_i$ axis the quantity indicated above the color bar is plotted using the scale of the bar.
• Figure 4: Schematic of the asymptotic-in state for the actual waveguide (a), the asymptotic-out for the actual waveguide (b), the asymptotic-out for the first phantom waveguide (c), and the asymptotic-out for the second phantom waveguide (d).