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arXiv · 2303.18092

Three-Path Quantum Cheshire Cat Observed in Neutron Interferometry

Armin Danner·Niels Geerits·Hartmut Lemmel·Richard Wagner·Stephan Sponar·Yuji Hasegawa
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Abstract

The paradoxical phenomenon of the quantum Cheshire Cat (qCC) refers to situations where different properties of a particle appear to be localised in different paths of an interferometer and therefore spatially separated. This observation is obtained by implementing a pre- and postselection procedure. The localisations are determined qualitatively through conspicuous changes induced by weak interactions. Previous demonstrations of the qCC only used the path and spin/polarisation degrees of freedom. In addition, the present experiment uses the neutron's energy as a third property in a three-path interferometer. It is demonstrated that the three properties of neutrons are found separated in different paths in the interferometer; a detailed analysis suggests that the appearance of a property is strongly related to the geometrical relation between the state vectors of pre- and postselection with weak interactions in between. If a weak interaction in a path locally generates a state vector with a component parallel to the reference state in another path, a conspicuous intensity oscillation is expected and observed. Therefore, the appearance of the observed intensity oscillations is attributed solely to the cross-terms between the reference and the newly generated state via weak interactions.

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Armin Danner, Niels Geerits, Hartmut Lemmel, Richard Wagner, Stephan Sponar, Yuji Hasegawa. 2023-03-31. Three-Path Quantum Cheshire Cat Observed in Neutron Interferometry. https://arxiv.org/abs/2303.18092

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