Complementarity and quantum erasure in an atom interferometer 1 Dedicated to Marlan O. Scully on the

We report on experiments with an atom interferometer, where the atom's spin is used as a marker for the atom's way through the interferometer. A measurement on this which-way marker allows us to acquire which-way knowledge. The choice of the measured observable determines how much which-way knowledge is obtained. In a quantum eraser, in particular, the observable is chosen so that no which-way knowledge is obtained. This allows us to regain interference fringes in subensembles of atoms, which are sorted according to the result of the measurement on the which-way marker. Here we focus on intermediate situations where the which-way information is only partially erased. We quantitatively compare the which-way knowledge obtained in such a measurement with the visibilities of the resulting interference patterns. The experimental data are in good agreement with two fundamental inequalities, one recently derived by Bjork and Karlsson [1], the other introduced here.

[1]  A. Zeilinger,et al.  Direct observation of fermion spin superposition by neutron interferometry , 1983 .

[2]  M. Scully,et al.  Quantum eraser: A proposed photon correlation experiment concerning observation and , 1982 .

[3]  Daniel M. Greenberger,et al.  Simultaneous wave and particle knowledge in a neutron interferometer , 1988 .

[4]  Herzog,et al.  Complementarity and the quantum eraser. , 1995, Physical review letters.

[5]  G. Rempe,et al.  Origin of quantum-mechanical complementarity probed by a ‘which-way’ experiment in an atom interferometer , 1998, Nature.

[6]  S. Haroche.  Quantum beats and time-resolved fluorescence spectroscopy , 1976 .

[7]  B. Englert,et al.  Quantum optical tests of complementarity , 1991, Nature.

[8]  R. Glauber,et al.  Amplifiers, Attenuators, and Schrödinger's Cat a , 1986 .

[9]  Rauch,et al.  Stochastic and deterministic absorption in neutron-interference experiments. , 1987, Physical review. A, General physics.

[10]  L. Garlaschelli,et al.  Working bloody miracles , 1991, Nature.

[11]  Koichi Shimoda,et al.  High-Resolution Laser Spectroscopy , 1976 .

[12]  Vaidman,et al.  Two interferometric complementarities. , 1995, Physical review. A, Atomic, molecular, and optical physics.

[13]  Gerald Badurek,et al.  Verification of coherent spinor rotation of fermions , 1975 .

[14]  Wineland,et al.  Young's interference experiment with light scattered from two atoms. , 1993, Physical review letters.

[15]  B. Englert,et al.  Fringe Visibility and Which-Way Information: An Inequality. , 1996, Physical review letters.

[16]  Rauch,et al.  Neutron interferometric double-resonance experiment. , 1986, Physical review. A, General physics.

[17]  L. Mandel,et al.  Induced coherence and indistinguishability in optical interference. , 1991, Physical review letters.

[18]  William K. Wootters,et al.  Complementarity in the double-slit experiment: Quantum nonseparability and a quantitative statement of Bohr's principle , 1979 .

[19]  Dreyer,et al.  Observing the Progressive Decoherence of the "Meter" in a Quantum Measurement. , 1996, Physical review letters.

[20]  L. S. Bartell.  COMPLEMENTARITY IN THE DOUBLE SLIT EXPERIMENT: ON SIMPLE REALIZABLE SYSTEMS FOR OBSERVING INTERMEDIATE PARTICLE WAVE BEHAVIOR , 1980 .

[21]  Steinberg,et al.  Observation of a "quantum eraser": A revival of coherence in a two-photon interference experiment. , 1992, Physical review. A, Atomic, molecular, and optical physics.

[22]  Remarks on Some Basic Issues in Quantum Mechanics , 1999 .

[23]  L. Mandel,et al.  Coherence and indistinguishability. , 1991, Optics letters.

[24]  V. Umansky,et al.  Dephasing in electron interference by a ‘which-path’ detector , 1998, Nature.

[25]  G. Rempe,et al.  Fringe Visibility and Which-Way Information in an Atom Interferometer , 1998 .

[26]  A. Karlsson,et al.  Complementarity and quantum erasure in welcher Weg experiments , 1998 .