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Physica E Low-dimensional Systems and Nanostructures

Relaxation processes in solid-state two-qubit gates

Elisabetta Paladino, Antonio D’Arrigo, Andrea Mastellone, G. Falci

Published Jun 25, 2009• 5 citations
Publisher
DOI
10.1016/j.physe.2009.06.042

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A quantum logical NOT and a conditional two-qubit gate (CROT), are implemented with single spins in a solid. As quantum bits a single electron spin and a single 13C nuclear spin of a single nitrogen vacancy defect center in diamond are used. The quantum state of the electron spin can be read out optically. Owing to long decoherence and relaxation times the systems meets the requirements of hardware for quantum computation. Density matrix tomography of the CROT gate shows that the achieved performance of the two bit conditional quantum gate is promising. The gate fidelity achieved in our experiments is up to 0.9, good enough to be used in quantum algorithms. Further on, the system may allow for solid-state room temperature quantum computation
Josephson junctions have been shown to be a promising solid-state system for implementation of quantum computation. The two-qubit gates are generally realized by the capacitive coupling between the nearest-neighbor qubits. We propose an effective Hamiltonian to describe charge qubits coupled through the microwave cavity. We find that nontrivial two-qubit gates may be achieved by this coupling. The ability to interconvert localized charge qubits and flying qubits in the proposed scheme implies that quantum network can be constructed using this large scalable solid-state system.