Reflection and transmission in a neutron-spin test of the quantum Zeno effect

Ken Machida, Hiromichi Nakazato, Saverio Pascazio, Helmut Rauch, Sixia Yu

Research output: Contribution to journalArticlepeer-review

22 Citations (Scopus)


The dynamics of a quantum system undergoing frequent “measurements,” leading to the so-called quantum Zeno effect, is examined on the basis of a neutron-spin experiment recently proposed for its demonstration. Unlike in all previous studies, the spatial degrees of freedom of the neutron are duly taken into account. Their inclusion in the analysis is important for two reasons: first, neutron-reflection effects are shown to be very important; second, the evolution may turn out to be totally different from the ideal case. Our results can be interpreted in terms of a rigorous theorem due to Misra and Sudarshan: indeed we clarify that, in contrast with a widespread belief, a quantum Zeno effect does not halt the evolution of a quantum system; it rather modifies it, by forcing the system to remain in a certain subspace, defined by the very measurement performed.

Original languageEnglish
Pages (from-to)3448-3460
Number of pages13
JournalPhysical Review A - Atomic, Molecular, and Optical Physics
Issue number5
Publication statusPublished - 1999

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics


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