title: Observing interferences between past and future quantum states in resonance fluorescence.
abstract: The fluorescence of a resonantly driven superconducting qubit is measured in the time domain, providing a weak probe of the qubit dynamics. Prior preparation and final, single-shot measurement of the qubit allows us to average fluorescence records conditionally on past and future knowledge. The resulting interferences reveal purely quantum features characteristic of weak values. We demonstrate conditional averages that go beyond classical boundaries and probe directly the jump operator associated with relaxation. The experimental results are remarkably captured by a recent theory, which generalizes quantum mechanics to open quantum systems whose past and future are known.
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: P
authors.initials: P
authors.lastname: Campagne-Ibarcq
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: L
authors.initials: L
authors.lastname: Bretheau
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: E
authors.initials: E
authors.lastname: Flurin
authors.affiliation: CNRS and Université Grenoble Alpes, Institut Néel, 38042 Grenoble, France.
authors.forename: A
authors.initials: A
authors.lastname: Auffèves
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: F
authors.initials: F
authors.lastname: Mallet
authors.affiliation: Laboratoire Pierre Aigrain, Ecole Normale Supérieure, CNRS (UMR 8551), Université Pierre et Marie Curie, Université Denis Diderot 24, rue Lhomond, 75231 Paris Cedex 05, France.
authors.forename: B
authors.initials: B
authors.lastname: Huard