A possible mechanism of concurring diagonal and off-diagonal long-range order for soft interactions

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dc.creatorSuto, Andras
dc.date2008-05-15
dc.date2009-04-17
dc.date.accessioned2026-07-07T13:04:36Z
dc.date.available2026-07-07T13:04:36Z
dc.descriptionThis paper is a contribution to the theory of coherent crystals. We present arguments claiming that negative minima in the Fourier transform of a soft pair interaction may give rise to the coexistence of diagonal and off-diagonal long-range order at high densities, and that this coexistence may be detectable due to a periodicity seen on the off-diagonal part of the one-body reduced density matrix, without breaking translation invariance. As an illustration, we study the ground state of a homogenous system of bosons in continuous space, from the interaction retaining only the Fourier modes $v(\k)$ belonging to a single nonzero wave number $|\k|=q$. The result is a mean-field model. We prove that for $v(\k)>0$ the ground state is asymptotically fully Bose-condensed, while for $v(\k)<0$ at densities exceeding a multiple of $\hbar^2 q^2/2m|v(\k)|$ it exhibits both Bose-Einstein condensation and diagonal long-range order, and the latter can be seen on both the one- and the two-body density matrix.
dc.descriptionpublished version
dc.identifierhttps://arxiv.org/abs/0805.2339
dc.identifierhttp://arxiv.org/abs/0805.2339
dc.identifierJ. Math. Phys. 50, 032107 (2009)
dc.identifier.urihttp://salesiana.dossiersoluciones.com/handle/123456789/227220
dc.subjectStatistical Mechanics
dc.subjectSuperconductivity
dc.titleA possible mechanism of concurring diagonal and off-diagonal long-range order for soft interactions
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