@article{HobanCampbellLoukopoulosetal.2011, author = {Hoban, Matty J. and Campbell, Earl T. and Loukopoulos, Klearchos and Browne, Dan E.}, title = {Non-adaptive measurement-based quantum computation and multi-party Bell inequalities}, series = {New journal of physics : the open-access journal for physics}, volume = {13}, journal = {New journal of physics : the open-access journal for physics}, number = {1}, publisher = {IOP Publ. Ltd.}, address = {Bristol}, issn = {1367-2630}, doi = {10.1088/1367-2630/13/2/023014}, pages = {18}, year = {2011}, abstract = {Quantum correlations exhibit behaviour that cannot be resolved with a local hidden variable picture of the world. In quantum information, they are also used as resources for information processing tasks, such as measurement-based quantum computation (MQC). In MQC, universal quantum computation can be achieved via adaptive measurements on a suitable entangled resource state. In this paper, we look at a version of MQC in which we remove the adaptivity of measurements and aim to understand what computational abilities remain in the resource. We show that there are explicit connections between this model of computation and the question of non-classicality in quantum correlations. We demonstrate this by focusing on deterministic computation of Boolean functions, in which natural generalizations of the Greenberger-Horne-Zeilinger paradox emerge; we then explore probabilistic computation via, which multipartite Bell inequalities can be defined. We use this correspondence to define families of multi-party Bell inequalities, which we show to have a number of interesting contrasting properties.}, language = {en} } @article{Campbell2011, author = {Campbell, Earl T.}, title = {Catalysis and activation of magic states in fault-tolerant architectures}, series = {Physical review : A, Atomic, molecular, and optical physics}, volume = {83}, journal = {Physical review : A, Atomic, molecular, and optical physics}, number = {3}, publisher = {American Physical Society}, address = {College Park}, issn = {1050-2947}, doi = {10.1103/PhysRevA.83.032317}, pages = {12}, year = {2011}, abstract = {In many architectures for fault-tolerant quantum computing universality is achieved by a combination of Clifford group unitary operators and preparation of suitable nonstabilizer states, the so-called magic states. Universality is possible even for some fairly noisy nonstabilizer states, as distillation can convert many noisy copies into fewer purer magic states. Here we propose protocols that exploit multiple species of magic states in surprising ways. These protocols provide examples of previously unobserved phenomena that are analogous to catalysis and activation well known in entanglement theory.}, language = {en} }