Modern photonics, the science of generating, controlling and detecting light, challenges technological limits and the immense role that electronics plays in every aspect of our lives. It emerges as a mainstream platform for integrated on-chip systems for communications, data storage, sensing, medical, energy, and defense applications. Photonics aims to replace electrons with photons thus replacing energy consuming electronic computer chips with much faster, greener, all-optical alternatives. To be efficient and cost-effective the integrated opto-electronic and all-optical photonic elements need to be scaled down to a few nanometers while maintaining superior functionality. This is where several fundamental physical limits have to be surmounted in order to achieve the breakthrough in technology.