title: Exact two-qubit universal quantum circuit.
abstract: We provide an analytic way to implement any arbitrary two-qubit unitary operation, given an entangling two-qubit gate together with local gates. This is shown to provide explicit construction of a universal quantum circuit that exactly simulates arbitrary two-qubit operations in SU(4). Each block in this circuit is given in a closed form solution. We also provide a uniform upper bound of the applications of the given entangling gates, and find that exactly half of all the controlled-unitary gates satisfy the same upper bound as the CNOT gate. These results allow for the efficient implementation of operations in SU(4) required for both quantum computation and quantum simulation.
authors.affiliation: Department of Electrical Engineering and Computer Sciences, University of California, Berkeley, California 94720, USA.
authors.forename: Jun
authors.initials: J
authors.lastname: Zhang
authors.forename: Jiri
authors.initials: J
authors.lastname: Vala
authors.forename: Shankar
authors.initials: S
authors.lastname: Sastry
authors.forename: K Birgitta
authors.initials: KB
authors.lastname: Whaley