Conference »Quantum Physics of Nature« (QUPON 2005) Mitschnitt einer Veranstaltung der Fakultät für Physik der Universität Wien am Sonntag, dem 22. Mai 2005 im Großen Festsaal der Universität Wien Teil 16: Helmut Rauch: Neutron interferometry reveals some quantum mystics Abstract: Neutrons are massive particles which couple to the environment by gravitational, strong and electroweak interactions. Highly efficient detectors, polarizers and spin rotators permit the realization of almost complete quantum experiments. In this respect neutrons are ideal tools for the observation of quantum phenomena with massive particles. Many pioneering experiments in quantum optics were first performed with neutrons, like the observation of the 4-pi-symmetry of spinors, the spin-superposition law, the magnetic Josephson effect and various post-selection experiments. Most of these experiments have employed perfect crystal neutron interferometers in which widely separated coherent beams can be manipulated individually. More recently, a confinement induced neutron phase has been measured that results from the transverse quantization of the neutron wave-function between narrow slits, indicating that neutrons are influenced by the walls although classically they do not touch them. This demonstrates the non-local feature of quantum mechanics and stimulated work to demonstrate, for the first time, the property of quantum contextuality, which means that even commuting variables can be correlated (entangled). The experimental results indicate that locality has to be treated in phase space rather than in ordinary space only. Dephasing and post-selection experiments have shown that a complete retrieval of a quantum state becomes impossible in principle just due to unavoidable quantum losses. Various quantum optics methods can be adapted to neutrons, like quantum state reconstruction, quantum state engineering, phase space compression and phase space transformation. Helmut Rauch ist Vorstand des Atominstituts der Österreichischen Universitäten. INHALT ====== Kapitel Titel Position --------------------------------------------------------------------- 1. Vorspann 00:00:00 2. Neutron interferometry 00:00:09 3. Wigner functions 00:06:17 4. Dephasing 00:10:23 5. Confinement effects 00:14:38 6. Contextuality experiments. Spin state tomography 00:18:23 7. Questions from the audience 00:28:49

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