Measurement-based quantum computing beyond the one-way model
Jens Eisert
Imperial College London, United Kingdom
Abstract: We establish a framework which allows one to systematically construct novel schemes for measurement-based quantum computation. The technique utilizes tools from many-body physics - based on finitely correlated or projected entangled pair states - to go beyond the cluster-state based one-way computer. We identify universal resource states with radically different entanglement properties than the cluster state, and computational models where the randomness is compensated in a different manner. It is shown that there exist universal resource states which are locally arbitrarily close to a pure state. We find that non-vanishing two-point correlation functions are no obstacle to universality. An explicit example for a resource state is presented, which can partly be prepared by gates with non-maximal entangling power.
In the last part of the talk, we discuss in detail the possibility of tailoring computational models to specific physical systems. This is most relevant for optical systems, as well as for systems of ultracold atoms in optical lattices: Intriguingly, it turns out that states that can be experimentally prepared in a fashion less prone to temperature effects and decoherence can serve as alternative resources for measurement-based quantum computing, different from the cluster state. In the outlook, Finally, we will have a brief look at a strategy to avoid feedforward in optical measurement-based computing, based on ideas from renormalization and percolation.