Optimal Two-Qubit Circuits for Universal Fault-Tolerant Quantum Computation

Understand

We study two-qubit circuits over the Clifford+CS gate set, which consists of the Clifford gates together with the controlled-phase gate CS=diag(1,1,1,i).

• The Clifford+CS gate set is universal for quantum computation and its elements can be implemented fault-tolerantly in most error-correcting schemes through magic state distillation.
• Since non-Clifford gates are typically more expensive to perform in a fault-tolerant manner, it is often desirable to construct circuits that use few CS gates.
• In the present paper, we introduce an efficient and optimal synthesis algorithm for two-qubit Clifford+CS operators.