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In this paper, we present recent progress in the growth, modelling, fabrication and characterization of gallium arsenide (GaAs) two-dimensional (2D) photonic-crystal slab cavities with embedded indium arsenide (InAs) quantum dots (QDs) that are designed for cavity quantum electrodynamics (cQED) experiments. Photonic-crystal modelling and device fabrication are discussed, followed by a detailed discussion of different failure modes that lead to photon loss. It is found that, along with errors introduced during fabrication, other significant factors such as the presence of a bottom substrate and cavity axis orientation with respect to the crystal axis, can influence the cavity quality factor (Q). A useful diagnostic tool in the form of contour finite-difference time domain (FDTD) is employed to analyse device performance.

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A large obstacle for realizing quantum photonic logic is the weak optical nonlinearity of available materials, which results in large power consumption. In this paper, we present the theoretical design of all-optical logic with second order (χ (2) ) nonlinear bimodal cavities and their networks. Using semiclassical models derived from the Wigner quasi-probability distribution function, we analyze the power consumption and signal-to-noise ratio (SNR) of networks implementing an optical AND gate and an optical latch. Comparison between the second and third order (χ (3) ) optical logic reveals that while the χ (3) design outperforms the χ (2) design in terms of the SNR for the same input power, employing the χ (3) nonlinearity necessitates the use of cavities with ultra high quality factors (Q ∼ 10 6 ) to achieve gate power consumption comparable to that of the χ (2) design at significantly smaller quality factors (Q ∼ 10 4 ). Using realistic estimates of the χ (2) and χ (3) nonlinear susceptibilities of available materials, we show that at achievable quality factors (Q ∼ 10 4 ), the χ (2) design is an order of magnitude more energy efficient than the corresponding χ (3) design.