title: Deterministic entanglement of photons in two superconducting microwave resonators.
abstract: Quantum entanglement, one of the defining features of quantum mechanics, has been demonstrated in a variety of nonlinear spinlike systems. Quantum entanglement in linear systems has proven significantly more challenging, as the intrinsic energy level degeneracy associated with linearity makes quantum control more difficult. Here we demonstrate the quantum entanglement of photon states in two independent linear microwave resonators, creating N-photon NOON states (entangled states |N0> + |0N>) as a benchmark demonstration. We use a superconducting quantum circuit that includes Josephson qubits to control and measure the two resonators, and we completely characterize the entangled states with bipartite Wigner tomography. These results demonstrate a significant advance in the quantum control of linear resonators in superconducting circuits.
authors.affiliation: Department of Physics, University of California, Santa Barbara, California 93106, USA.
authors.forename: H
authors.initials: H
authors.lastname: Wang
authors.forename: Matteo
authors.initials: M
authors.lastname: Mariantoni
authors.forename: Radoslaw C
authors.initials: RC
authors.lastname: Bialczak
authors.forename: M
authors.initials: M
authors.lastname: Lenander
authors.forename: Erik
authors.initials: E
authors.lastname: Lucero
authors.forename: M
authors.initials: M
authors.lastname: Neeley
authors.forename: A D
authors.initials: AD
authors.lastname: O'Connell
authors.forename: D
authors.initials: D
authors.lastname: Sank
authors.forename: M
authors.initials: M
authors.lastname: Weides
authors.forename: J
authors.initials: J
authors.lastname: Wenner
authors.forename: T
authors.initials: T
authors.lastname: Yamamoto
authors.forename: Y
authors.initials: Y
authors.lastname: Yin
authors.forename: J
authors.initials: J
authors.lastname: Zhao
authors.forename: John M
authors.initials: JM
authors.lastname: Martinis
authors.forename: A N
authors.initials: AN
authors.lastname: Cleland