Scientists are making some headway in building quantum computers using holograms. By exploiting the unusual characteristics of quantum mechanics, quantum computers could potentially crank out calculations a billion times faster than today's integrated circuits. The power of quantum computers lies in the ability of a quantum bit (qubit) to exist in a zero or one state, or a superposition somewhere in the middle, or, oddly, both at one time. For many years, researchers have studied how to use photons to carry quantum information in these futuristic computers. The challenge is that the optical devices used in this approach, interferometers, are so sensitive that they get out of alignment if someone looks at them wrong. Now though, scientists from the Air Force Research Laboratory suggest that by embedding interferometers in glass — essentially storing them as "holograms" — will keep them stable. What's especially cool is that they can make these quantum computers — albeit very simple ones — using an off-the-shelf holographic materials from a company called OptiGrate. From Tech Review:
MacDonald and co suggest using a commercial holographic material called OptiGrate to store these holograms and show how these devices could carry out simple tasks such as quantum teleportation and CNOT logic.
There are two serious limitations to this approach, however. First, these devices are not scalable. The reason is that a hologram requires a certain volume of space to carry out each computation with high fidelity. And since computations scale exponentially in quantum computers, so must the volume.
Second, these devices are not reprogrammable, at least not with today's technology…
But there are a number of emerging applications for the kind of reliable but low-dimensional quantum computations that these devices could perform. These include quantum memory buses, quantum error correction circuits and quantum key distribution relays.
"Quantum Computing With Holograms" (Physics arXiv Blog)
"Quantum computing in a piece of glass" (arXiv.org)
