The blurring effects of diffraction pose an obstacle to transmitting an image with all-optical technology. A method to reduce diffraction that takes advantage of the thermal motion of atoms could prove a way to keep images sharp.
Metamaterials can be designed to rotate light as it passes through them. If the effect is strong enough, it can lead to the material having a negative index of refraction and light bouncing around very differently than expected.
Preparing a harmonic oscillator in a state with a well-defined energy is a tricky business. With the new tools provided by cavity and circuit quantum electrodynamics it is now possible to make these pure quantum states and watch how they evolve in time.