Efficient purification protocols using iSWAP gates in solid-state qubits

We show an efficient purification protocol in solid-state qubits by replacing the usual bilateral controlled-NOT gate by the bilateral iSWAP gate. We also show that this replacement can be applied to breeding and hashing protocols, which are useful for quantum state purification. These replacements reduce the number of fragile and cumbersome two-qubit operations, making more feasible quantum-information processing with solid-state qubits. As examples, we also present quantitative analyses for the required time to perform state purification using either superconducting or semiconducting qubits.