Two-qubit decoherence mechanisms revealed via quantum process tomography
Abraham G. Kofman, Alexander N. Korotkov · Physical Review A · 2009
We analyze the quantum process tomography (QPT) in the presence of decoherence, focusing on distinguishing local and nonlocal decoherence mechanisms for a two-partite system from experimental QPT data. In particular, we consider the $\sqrt{i\text{SWAP}}$ gate realized with superconducting phase qubits and calculate the QPT matrix $\ensuremath{\chi}$ in the presence of several local and nonlocal decoherence processes. We determine specific patterns of these decoherence processes, which can be used for a fast identification of the main decoherence mechanisms from an experimental $\ensuremath{\chi}$ matrix.