title: Linear-optical simulation of the cooling of a cluster-state Hamiltonian system.
abstract: A measurement-based quantum computer could consist of a local-gapped Hamiltonian system, whose thermal states-at sufficiently low temperature-are universal resources for the computation. Initialization of the computer would correspond to cooling the system. We perform an experimental quantum simulation of such a cooling process with entangled photons. We prepare three-qubit thermal cluster states exploiting the equivalence between local dephasing and thermalization for these states. This allows us to tune the system's temperature by changing the dephasing strength. We monitor the entanglement as the system cools down and observe the transitions from separability to bound entanglement, and then to free entanglement. We also analyze the performance of the system for measurement-based single-qubit state preparation. These studies constitute a basic characterization of experimental cluster-state computation under imperfect conditions.
authors.affiliation: Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil.
authors.forename: G H
authors.initials: GH
authors.lastname: Aguilar
authors.affiliation: Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil.
authors.forename: T
authors.initials: T
authors.lastname: Kolb
authors.affiliation: ICFO-Institut de Ciencies Fotoniques, 08860 Castelldefels (Barcelona), Spain.
authors.forename: D
authors.initials: D
authors.lastname: Cavalcanti
authors.affiliation: Dahlem Center for Complex Quantum Systems, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Aolita
authors.affiliation: Institute for Physics, University of Freiburg, Rheinstrasse 10, D-79104 Freiburg, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Chaves
authors.affiliation: Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil.
authors.forename: S P
authors.initials: SP
authors.lastname: Walborn
authors.affiliation: Instituto de Física, Universidade Federal do Rio de Janeiro, Caixa Postal 68528, Rio de Janeiro, RJ 21941-972, Brazil.
authors.forename: P H
authors.initials: PH
authors.lastname: Souto Ribeiro