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Quantum Circuits for General Multiqubit Gates

Mikko Mottonen·Juha J. Vartiainen·Ville Bergholm·Martti M. Salomaa
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Abstract

We consider a generic elementary gate sequence which is needed to implement a general quantum gate acting on n qubits -- a unitary transformation with 4^n degrees of freedom. For synthesizing the gate sequence, a method based on the so-called cosine-sine matrix decomposition is presented. The result is optimal in the number of elementary one-qubit gates, 4^n, and scales more favorably than the previously reported decompositions requiring 4^n-2^n+1 controlled NOT gates.

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Mikko Mottonen, Juha J. Vartiainen, Ville Bergholm, Martti M. Salomaa. 2004-10-29. Quantum Circuits for General Multiqubit Gates. https://doi.org/10.1103/physrevlett.93.130502

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