So you take advantage of that change. When the chiral molecules are dissolved in liquid crystal and exposed to modest amounts of polarized-light energy, they cause a phase change in the liquid crystal, like the phase change that takes place when water turns to ice. That is how such things as liquid-crystal computer screens display images, although that type of phase change is induced with electricity. We start with a 50-50 mixture, and then when we have an excess of one kind of molecule or the other, that induces the phase transition in the liquid crystal. The phase transition is then sensed optically.
Much work remains, however, before the memory cube becomes reality.
For example, Schuster says he isn't sure yet just how the switches will be useful for an optical memory system. I think the reality is that it is only going to be useful if you can do it in three dimensions. Furthermore, that would be useful only if you don't have to write information a bit at a time, which means writing it holographically. If you could write three-dimensional holograms optically, then you would really have something worthwhile. While traditional memory media can hold about 100 million bits of information per square centimeter, a three-dimensional medium could hold a trillion bits in the same space.