Abstract
We prove that a unitary matrix has an exact representation over the Clifford+ gate set with local ancillas if and only if its entries are in the ring . Moreover, we show that one ancilla always suffices. These facts were conjectured by Kliuchnikov, Maslov, and Mosca. We obtain an algorithm for synthesizing a exact Clifford+ circuit from any such -qubit operator. We also characterize the Clifford+ operators that can be represented without ancillas.
- Received 4 December 2012
DOI:https://doi.org/10.1103/PhysRevA.87.032332
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