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Journal of Computational and Theoretical Nanoscience, 7 (2010) 1759-1770
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Unitary reflection groups for quantum fault tolerance
Michel Planat1, Maurice R. Kibler2

This paper explores the representation of quantum computing in terms of unitary reflections (unitary transformations that leave invariant a hyperplane of a vector space). The symmetries of qubit systems are found to be supported by Euclidean real reflections (i.e., Coxeter groups) or by specific imprimitive reflection groups, introduced (but not named) in a recent paper [Planat M and Jorrand Ph 2008, {\it J Phys A: Math Theor} {\bf 41}, 182001]. The automorphisms of multiple qubit systems are found to relate to some Clifford operations once the corresponding group of reflections is identified. For a short list, one may point out the Coxeter systems of type $B_3$ and $G_2$ (for single qubits), $D_5$ and $A_4$ (for two qubits), $E_7$ and $E_6$ (for three qubits), the complex reflection groups $G(2^l,2,5)$ and groups No $9$ and $31$ in the Shephard-Todd list. The relevant fault tolerant subsets of the Clifford groups (the Bell groups) are generated by the Hadamard gate, the $\pi/4$ phase gate and an entangling (braid) gate [Kauffman L~H and Lomonaco S~J 2004 {\it New J. of Phys.} {\bf 6}, 134]. Links to the topological view of quantum computing, the lattice approach and the geometry of smooth cubic surfaces are discussed.
1 :  FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies
2 :  IPNL - Institut de Physique Nucléaire de Lyon
Physique/Physique Quantique

Mathématiques/Physique mathématique

Physique/Physique mathématique

Mathématiques/Théorie des groupes
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