Quantum contextuality
Recently, quantum contextuality has been explored as a potential tool for quantum computing. In 2013, Robert Raussendorf showed that in general, any Mermin-like, inequality-free proof for quantum contextuality (such as the Kochen-Specker theorem) can be turned into a measurement-based quantum computation. More formally, "under quite natural assumptions for multi-qubit systems, MBQCs (measurement based quantum computations) which compute a non-linear Boolean function with sufficiently high success probability are contextual." Then in 2014, Mark Howard, et. al. showed that applying contextuality to magic state distillation (MSD) provides a means for arriving at universal, fault-tolerant quantum computing. MSD is a process by which a single qubit's polarization is increased along one of several "magic" directions and its state is considered "magic" once its polarization reaches a certain level. In particular, the group proved that states are non-contextual if and only if they cannot be used as inputs for magic state distillation. This provides a selection criteria for proper input states needed in MSD, and by extension aids in the efficient creation of magic states that, when coupled with fault-tolerant operators, allows for universal quantum computing. In both cases, contextuality has a potential advantage over other quantum computational techniques since contextuality itself can be thought of as a theory of information that is built directly into quantum mechanics. Comparatively, more traditional quantum phenomena such as entanglement and interference use delicate physical states which are incredibly susceptible to noise and very difficult to manipulate experimentally.
Centre for Quantum Computation
Initially the CQC was based at the Clarendon Laboratory, but it has now grown to span several departments at the University of Oxford:The Centre has its origins in the early 80's when the computer industry began to worry about the limits of computing. In 1981, Oxford physicist David Deutsch attended a party in Texas given by the famous American physicist John Wheeler who had invited a number of scientists interested in the foundations of computing. It was at this party that Deutsch gained the crucial insight that would lead to an entirely new branch of physics. At the time, computer scientists were turning to Newtonian physics to try to resolve certain fundamental puzzles in the field. But during a conversation at Wheeler’s party, Deutsch realised that this was the wrong approach. Physics is fundamentally governed by quantum theory, and Deutsch could see immediately that using quantum theory instead of Newtonian physics would give a different result. As a consequence of this insight, Deutsch published the paper in 1985 that is now generally regarded as a classic in the field. The paper describes how a computer might run using quantum mechanics and why such a computer is fundamentally different from ordinary computers.