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Phys. Rev. A 80, 062328 (2009) [8 pages]

Transitions in the computational power of thermal states for measurement-based quantum computation

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Sean D. Barrett1, Stephen D. Bartlett2, Andrew C. Doherty3, David Jennings2, and Terry Rudolph1,4
1Optics Section, Blackett Laboratory, Imperial College London, London SW7 2BZ, United Kingdom
2School of Physics, The University of Sydney, Sydney, New South Wales 2006, Australia
3School of Physical Sciences, The University of Queensland, St. Lucia, Queensland 4072, Australia
4Institute for Mathematical Sciences, Imperial College London, London SW7 2BW, United Kingdom

Received 16 March 2009; published 18 December 2009

We show that the usefulness of the thermal state of a specific spin-lattice model for measurement-based 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 spin-lattice model.

© 2009 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevA.80.062328
DOI:
10.1103/PhysRevA.80.062328
PACS:
03.67.Lx, 03.65.Ta, 05.50.+q, 73.43.Nq
 
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