title: Experimental Demonstration of Direct Path State Characterization by Strongly Measuring Weak Values in a Matter-Wave Interferometer.
abstract: A method was recently proposed and experimentally realized for characterizing a quantum state by directly measuring its complex probability amplitudes in a particular basis using so-called weak values. Recently, Vallone and Dequal [Phys. Rev. Lett. 116, 040502 (2016)PRLTAO0031-900710.1103/PhysRevLett.116.040502] showed theoretically that weak measurements are not a necessary condition to determine the weak value. Here, we report a measurement scheme used in a matter-wave interferometric experiment in which the neutron path system's quantum state was characterized via direct measurements, using both strong and weak interactions. Experimental evidence is given that strong interactions outperform weak ones for tomographic accuracy. Our results are not limited to neutron interferometry, but can be used in a wide range of quantum systems.
authors.affiliation: AtomInstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria.
authors.forename: Tobias
authors.initials: T
authors.lastname: Denkmayr
authors.affiliation: AtomInstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria.
authors.forename: Hermann
authors.initials: H
authors.lastname: Geppert
authors.affiliation: AtomInstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria.|Institut Laue-Langevin, 6, Rue Jules Horowitz, 38042 Grenoble Cedex 9, France.
authors.forename: Hartmut
authors.initials: H
authors.lastname: Lemmel
authors.affiliation: Institute for Quantum Studies, Chapman University, Orange, California 92866, USA.
authors.forename: Mordecai
authors.initials: M
authors.lastname: Waegell
authors.affiliation: Institute for Quantum Studies, Chapman University, Orange, California 92866, USA.|Schmid College of Science and Technology, Chapman University, Orange, California 92866, USA.
authors.forename: Justin
authors.initials: J
authors.lastname: Dressel
authors.affiliation: AtomInstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Hasegawa
authors.affiliation: AtomInstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria.
authors.forename: Stephan
authors.initials: S
authors.lastname: Sponar