After a decade or so in the lab, holographic data storage is about to burst into the hardware market big time.
Its USP is that holographic data is stored globally rather than at specific sites in the storage medium.
It is written using a pair of lasers to create an interference pattern that is recorded in the storage medium. It can then viewed by illuminating that area with a laser to recreate the pattern. Crucially, you can add and view more data by changing the angle at which you address the medium and this gives huge storage potential.
Now Karl Tordrup and colleagues at the University of Aarhus in Denmark have used the idea as inspiration for the design of a quantum computer. Their machine consists of an array of molecules that can each store a qubit. But instead of addressing them individually, Tordrup imagines storing quantum data in them as a group, by zapping them with the right kind of laser-created interference pattern. This is essentially quantum data storage, the holographic way.
What makes the idea interesting is that the group reckons that information can be processed by transferrring it to a nearby superconducting box in which the required operations can be performed. The processed data is then sent back again.
The big advantage of this idea is that, while stored in holographic form, the quantum data is incredibly robust. While any single molecule errors affect all qubits, they do so only very weakly. It also means that the molecules need only be addressed as a group, not as individuals which does away with a significant challenge that other designs of computer face
But there are problems too. The qubits will have to be protected from decoherence while in the superconducting box and travelling to and from it. And although the molecules do not need to be addressed individually, they do need to be held almost perfectly still. Those are toughies.
All they need to do now is build the thing.
Ref: arxiv.org/abs/0802.4406: Holographic Quantum Computing