Complete characterization of the directly implementable quantum gates used in the IBM quantum processors

Quantum process tomography (QPT) of each directly implementable quantum gate used in the IBM quantum processors is performed to compute gate error in order to check viability of complex quantum operations in the superconductivity-based quantum computers introduced by IBM. QPT of C-NOT gates is performed for three configurations available in IBM QX4. For the other allowed gates QPT have been performed for every allowed position (i.e., by placing the gates in different qubit lines) for IBM QX4 architecture, and thus, gate fidelities are obtained. Gate fidelities are observed to be lower than the corresponding values obtained in the other technologies, like NMR. Further, gate fidelities for all the single-qubit gates are obtained for IBM QX2 architecture by placing the gates in the third qubit line (q[2]). It's observed that the IBM QX4 architecture yields better gate fidelity compared to IBM QX2 in all cases except Y gate. (C) 2020 Elsevier B.V. All rights reserved.