A neutron diffraction study of macroscopically entangled proton states in the high temperature phase of the KHCO3 crystal at 340 K

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dc.creatorFillaux, François
dc.creatorCousson, Alain
dc.creatorGutmann, Matthias J.
dc.date2008-07-09
dc.date.accessioned2026-07-07T09:49:20Z
dc.date.available2026-07-07T09:49:20Z
dc.descriptionWe utilize single-crystal neutron diffraction to study the $C2/m$ structure of potassium hydrogen carbonate (KHCO$_3$) and macroscopic quantum entanglement above the phase transition at $T_c = 318$ K. Whereas split atom sites could be due to disorder, the diffraction pattern at 340 K evidences macroscopic proton states identical to those previously observed below $T_c$ by F. Fillaux et al., (2006 \textit{J. Phys.: Condens. Matter} \textbf{18} 3229). We propose a theoretical framework for decoherence-free proton states and the calculated differential cross-section accords with observations. The structural transition occurs from one ordered $P2_1/a$ structure ($T < T_c$) to another ordered $C2/m$ structure. There is no breakdown of the quantum regime. It is suggested that the crystal is a macroscopic quantum object which can be represented by a state vector. Raman spectroscopy and quasi-elastic neutron scattering suggest that the $|C2/m>$ state vector is a superposition of the state vectors for two $P2_1/a$-like structures symmetric with respect to $(a,c)$ planes.
dc.identifierhttps://arxiv.org/abs/0807.1386
dc.identifierhttp://arxiv.org/abs/0807.1386
dc.identifierJournal of Physics Condensed Matter 20 (2007) 015225
dc.identifierdoi:10.1088/0953-8984/20/01/015225
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/164549
dc.subjectOther Condensed Matter
dc.subjectQuantum Physics
dc.titleA neutron diffraction study of macroscopically entangled proton states in the high temperature phase of the KHCO3 crystal at 340 K
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