Transitions in the computational power of thermal states for measurementbased quantum computation
Abstract
We show that the usefulness of the thermal state of a specific spinlattice model for measurementbased quantum computing exhibits a transition between two distinct “phases”—one in which every state is a universal resource for quantum computation, and another in which any local measurement sequence can be simulated efficiently on a classical computer. Remarkably, this transition in computational power does not coincide with any phase transition, classical, or quantum in the underlying spinlattice model.
 Publication:

Physical Review A
 Pub Date:
 December 2009
 DOI:
 10.1103/PhysRevA.80.062328
 arXiv:
 arXiv:0807.4797
 Bibcode:
 2009PhRvA..80f2328B
 Keywords:

 03.67.Lx;
 03.65.Ta;
 05.50.+q;
 73.43.Nq;
 Quantum computation;
 Foundations of quantum mechanics;
 measurement theory;
 Lattice theory and statistics;
 Quantum phase transitions;
 Quantum Physics
 EPrint:
 9 pages, 2 figures, v4 published version