Measurement of the entanglement of two superconducting qubits via state tomography.

Department of Physics and California Nano Systems Institute, University of California, Santa Barbara, CA 93106, USA.
Science (Impact Factor: 31.2). 10/2006; 313(5792):1423-5. DOI: 10.1126/science.1130886
Source: PubMed

ABSTRACT Demonstration of quantum entanglement, a key resource in quantum computation arising from a nonclassical correlation of states, requires complete measurement of all states in varying bases. By using simultaneous measurement and state tomography, we demonstrated entanglement between two solid-state qubits. Single qubit operations and capacitive coupling between two super-conducting phase qubits were used to generate a Bell-type state. Full two-qubit tomography yielded a density matrix showing an entangled state with fidelity up to 87%. Our results demonstrate a high degree of unitary control of the system, indicating that larger implementations are within reach.

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