title: Two-qubit state tomography using a joint dispersive readout.
abstract: Quantum state tomography is an important tool in quantum information science for complete characterization of multiqubit states and their correlations. Here we report a method to perform a joint simultaneous readout of two superconducting qubits dispersively coupled to the same mode of a microwave transmission line resonator. The nonlinear dependence of the resonator transmission on the qubit state dependent cavity frequency allows us to extract the full two-qubit correlations without the need for single-shot readout of individual qubits. We employ standard tomographic techniques to reconstruct the density matrix of two-qubit quantum states.
authors.affiliation: Department of Physics, ETH Zurich, CH-8093 Zurich, Switzerland. filipp@phys.ethz.ch
authors.forename: S
authors.initials: S
authors.lastname: Filipp
authors.forename: P
authors.initials: P
authors.lastname: Maurer
authors.forename: P J
authors.initials: PJ
authors.lastname: Leek
authors.forename: M
authors.initials: M
authors.lastname: Baur
authors.forename: R
authors.initials: R
authors.lastname: Bianchetti
authors.forename: J M
authors.initials: JM
authors.lastname: Fink
authors.forename: M
authors.initials: M
authors.lastname: Göppl
authors.forename: L
authors.initials: L
authors.lastname: Steffen
authors.forename: J M
authors.initials: JM
authors.lastname: Gambetta
authors.forename: A
authors.initials: A
authors.lastname: Blais
authors.forename: A
authors.initials: A
authors.lastname: Wallraff