title: Measurement of the entanglement of two superconducting qubits via state tomography.
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.
authors.affiliation: Department of Physics and California Nano Systems Institute, University of California, Santa Barbara, CA 93106, USA.
authors.forename: Matthias
authors.initials: M
authors.lastname: Steffen
authors.forename: M
authors.initials: M
authors.lastname: Ansmann
authors.forename: Radoslaw C
authors.initials: RC
authors.lastname: Bialczak
authors.forename: N
authors.initials: N
authors.lastname: Katz
authors.forename: Erik
authors.initials: E
authors.lastname: Lucero
authors.forename: R
authors.initials: R
authors.lastname: McDermott
authors.forename: Matthew
authors.initials: M
authors.lastname: Neeley
authors.forename: E M
authors.initials: EM
authors.lastname: Weig
authors.forename: A N
authors.initials: AN
authors.lastname: Cleland
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis