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Entangled protons in a crystal lattice

  1. Sep 28, 2009 #1
    Can entangled protons be maintained in a crystal lattice for an indefinite period of time?
    The following papers seem to support this contention.
    I need the help of the Forum’s readers to critique this research and the assertions the authors are making.

    Dr. Francois Fillauxa and Dr Alain Cousson in a paper titled "Where are protons and deuterons in KHpD1−pCO3? A neutron diffraction study" have claimed that "defect-free crystals are macroscopic quantum systems with discrete phonon states at any temperature below melting or decomposition. This is an unavoidable consequence of the translational invariance of the lattice." (see http://hal.archives-ouvertes.fr/docs/00/36/96/97/PDF/Fillaux.pdf" [Broken])

    This paper which was published in "Zeitschrift fuer Physikalische Chemie 222, 8-9 (2008) 1279-1290" then proceeds to make the following claims:
    "This ground state is intrinsically steady against decoherence. Irradiation by plane waves (photons or neutrons) may single out some excited states. Entanglement in position and momentum is preserved, while the spinsymmetry and super-rigidity are destroyed. However, the spin-symmetry reappears automatically after decay to the ground state, presumably on the time-scale of proton dynamics. Consequently, disentanglement reaches a steady regime such that the amount of transitory disentangled states is determined by the ratio of density-of-states for the surroundings (atmosphere, external radiations...) and for the crystal, respectively. This ratio is so small that disentangled states are too few to be observed. Nevertheless, they allow the super-rigid sublattice to be at thermal equilibrium with the surroundings, despite the lack of internal dynamics. The main source of disentanglement is the thermal population of excited proton states. However, even at room temperature, the thermal population of the first excited state (< 1% for OH ≈ 1000 cm−1) is of little impact to measurements."

    In an earlier paper titled "Macroscopic quantum entanglement and ‘super-rigidity’ of protons in the KHCO3 crystal from 30 to 300 K" from the “JOURNAL OF PHYSICS: CONDENSED MATTER” alleged "Quantum entanglement, still observed at 300 K, indicates that proton transfer is a thermally activated coherent superposition of macroscopic tunnelling states. This work adds a crystalline solid to the list of systems with ‘super’ properties.' (see http://www.ladir.cnrs.fr/pages/fillaux/152_JPCM_2006_3229.pdf" [Broken])

    A third paper titled "Proton transfer in the KHCO3 and benzoic acid crystals: A quantum view" builds on the 2006 paper cited above in the following: "Macroscopic entanglement has been evidenced for KHCO3, from 15 to 300 K, with neutron diffraction [20,22]." and states "In a perfect crystal, atoms are not individual particles possessing properties on their own right. They are entangled. The periodicity and indistinguishablility of lattice sites lead to extended states in three dimensions and nonlocal observables (for example phonons). There is no transition to the classical regime, as long as the crystal is stable, and disorder-free." (see http://www.glvt-cnrs.fr/ladir/pages/fillaux/158_JMS_2007_308.pdf" [Broken])

    This paper, which appeared in the Journal of Molecular Structure 844–845 (2007) 308–318, also claims that "There is no local information available for these macroscopically entangled states. In addition, they are intrinsically decoherence-free. Irradiation by photons, neutrons, etc, may single out some excited pseudoprotons, but as long as Eqs. (5) and (8) remain valid, entanglement in position and momentum is preserved. Only the spin-symmetry and super-rigidity, intrinsic to degenerate states, can be destroyed, but these properties are recovered automatically, after decay to the ground state, presumably on the time-scale of proton dynamics. This mechanism allows the sublattice to be at thermal equilibrium with the surroundings, despite the lack of internal dynamics."

    If the critique is favorable, the next question I would like to ask is whether the entangled protons might be subject to adiabatic manipulation?
    Any insights the readers may wish to share would be valued.

    Thank you.
    Last edited by a moderator: May 4, 2017
  2. jcsd
  3. Sep 28, 2009 #2


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  4. Sep 28, 2009 #3
    Dear Alxm:

    Thank you for your reply. Nonetheless, the alleged stability of the entangled protons seems difficult to believe. Can you (or any other readers of the Forum) assume the role of Devil's advocate and think of some reasons why the research or conclusions might be flawed? I don't want to build on these studies if the foundation is unsound.

    Thank you,

    Jon Trevathan
  5. Sep 28, 2009 #4


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    Seems http://www.iop.org/EJ/abstract/0953-8984/15/29/305/" paper by Keen and Lovesey disputes the theory of Fillaux/Cousson. They published a response to that, and Keen/Lovesey responded to their rebuke.

    So suffice to say there's some dispute about the matter. Both seem plausible to me, and given that I've not immersed myself in the exact details, I can't arbitrate. Given that I'm not an expert on neutron diffraction crystallography, I probably shouldn't attempt it.
    Last edited by a moderator: Apr 24, 2017
  6. Sep 28, 2009 #5
    Upon preliminary review, it appears Fillauxa and Cousson started the dispute by criticizing a paper by Keen and Lovesey. This critique then prompted a very short response by Keen and Lovesey. The dispute does not appear to directly question Fillauxa's research or findings. Also, the dispute appears to have predated the papers I am trying to evaluate. Following this brief exchange of papers (which occurred in 2003-4), Fillauxa appears to have continued his research unabated; and without apparent alteration to the direction of his research. Keen and Lovesey appear to have been less prolific. Nonetheless, I am very grateful you brought this controversy to my attention and have pulled several papers, including those the disputants exchanged, that I plan to more fully evaluate.

    If anyone else would like to critique Fillauxa's and Cousson's work or suggest papers I should review, I would love to read your comments.
  7. Oct 2, 2009 #6
    Although my interest in these papers will eventually focus on quantum computing, it my hope that the following questions will generate more interest; and critical review of the foregoing papers.

    Do the Fillauxa papers provide a theoretical basis that "explains" Quantum Entangled Thermoluminescence? I introduced a non-peer reviewed paper on Quantum Entangled Thermoluminescence under the title "Superluminal Communication" over a year ago which was savaged by the readers of this Forum; in part, because a theoretical foundation for the research was not presented. (see https://www.physicsforums.com/archive/index.php/t-250578.html"
    The topic received more extensive consideration at the following site, but remained suspect because a theoretical foundation was not provided.
    It is my belief that the Fillauxa papers may supply some theoretical basis for the Desbrandes and Van Gent papers I introduced.
    If I am wrong in this regard, it is my hope that the readers of the Forum will help me fully understand why I am in error

    Although, this is not an ultimate question for my purposes, it is my hope that it will generate some additional interest in the topic.
    The additional questions that follow are intended to provide some idea where the discussion might eventually lead -- if the research by Fillauxa and Cousson is deemed sound by the readers of this Forum.

    1. Given the extreme robustness of the entangled protons (as described in the Fillauxa and Cousson papers), is it reasonable to believe that a single chip might be split into an ensemble of chips, to the limit of n dimers per chip, without destroying the proton entanglement?

    2. Might the spin (or some other property) of the entangled protons in a "transmission chip" be adiabatic manipulated, and, if so, how?

    3. Assuming that the spin of the entangled protons in the "transmission chip" were adiabatic manipulated into the up direction, is it reasonable to believe that the spin of the entangled protons in the ensemble of "receptor chips" would all be in the down direction?

    4. How might we read the spin of the receptor chip? (This following is not a preferred embodiment but is indicative of one way in which proton spin may be "read". http://physicsworld.com/cws/article/news/19877.)

    4a. Assuming that we have an ensemble of "receptor chips", might the spin be determined using weak measurements? (see: "Non-statistical Weak Measurements" http://arxiv.org/abs/quant-ph/0607208; [Broken]
    "Weak measurements, weak values, and entanglement" http://link.aip.org/link/?PSISDG/6573/65730Z/1 [Broken]
    Pre-and post-selection, weak values and contextuality http://cat.inist.fr/?aModele=afficheN&cpsidt=18922792;
    and Robust Weak Measurements on Finite Samples http://arxiv.org/abs/quant-ph/0703038)

    4b. Assuming that the spin cannot be determined using weak measurements, is it reasonable to believe that a von Neumann measurement of any chip within the ensemble of "receptor chips" would reveal the spin of the entangled protons was in the down direction?

    4c. Would the acute perturbation described in 4b. destroy the entanglement of the entire ensemble?

    There are more questions to be addressed, but hopefully the foregoing will be sufficient to generate the critical review I am seeking

    Thank you,

    Jon Trevathan
    Last edited by a moderator: May 4, 2017
  8. Oct 3, 2009 #7
    The above statement was wrong. The initial paper of Keen and Lovesey directly questioned Fillauxa's and Cousson's interpretation of their data and the fact that the Fillauxa and Cousson papers I have been evaluating were subsequently published without more recent critique was not significant.

    Dr. Lovesay has, in a private communication, informed me that "Professor Keen was part of the team that gathered the data" and that he "believed then that their [the Fillauxa and Cousson] interpretation was erroneous and nothing has occurred to change my opinion." Dr. Lovesay additionally noted that he "wrote a short review about the observation of entanglement by scattering..." which I will need to spend some time with. The reference follows:

    Quantum-mechanical correlations between the nuclear spatial and spin degrees of freedom in a material as revealed by neutron scattering, S. W. Lovesey (2005) Physica Scripta 71, CC14

    I am very grateful to Dr. Lovesay for his gracious contribution and to alxm for introducing me to these papers.
  9. Oct 5, 2009 #8
    Our work on macroscopic quantum entanglement in the crystal of KHCO3 started more than 10 years ago with some theoretical speculation on coupled dimers of fermion oscillators, see F.Fillaux, Physica D, 113 (1998) 172, and the observation of interference fringes with neutron scattering (S.Ikeda and F.Fillaux, Phys.rev.B, 59 (1999) 4134). Then, we sought and found evidences of the macroscopic quantum entanglement of the sublattice of protons, from cryogenic to above room temperature (for a review, see arXiv:0903.4033v1).

    Our theory is based upon fundamental laws of quantum mechanics applied to the crystal in question, without any ad hoc hypothesis or parameter: the structure is periodic; dimers are centrosymmetric; indistinguishable protons are fermions; they are adiabatically separated from heavy atoms. It leads to macroscopically entangled states and, in the special case of protons, to super-rigidity and spin-symmetry with observable consequences (enhanced neutron diffraction). This theory is consistent with a large set of experimental data and, to the best of our knowledge, there is no conflict with any observation. There is, therefore, every reason to conclude that the crystal is a macroscopic quantum system for which only nonlocal observables are relevant. Protons are not classical particles. They merge into macroscopic states extended throughout the crystal.

    There are two alternative proposals. For Keen and Lovesey, entanglement should arise from quantum exchange between protons in dimers. This is simply incorrect because the exchange of protons separated by 2.2 A is merely 0. This was the main point of our comment and the reply did not provide any further light on this exchange mechanism. There are also many irrelevant claims in the Keen and Lovesey paper and it is clear that their theoretical scattering function is dramatically at variance with the observation.

    Alternatively, for Sugimoto et al., Phys. Rev. B 73 (2006) 014305, entanglement should arise from spin-spin coupling in dimers. This is also incorrect because this coupling of about 10 KHz is too weak to give any long-lived correlations.

    So far, there is no sounded alternative interpretation. In fact, quantum entanglement emerges naturally from the crystal structure, so there is no reason to introduce any further interaction. From the viewpoint of economy (Ockham's razor), alternative theories based upon quantum exchange or spin-spin interaction or any other ad hoc mechanism are less satisfactory, in addition to be irrelevant.

    I am not an expert but I do not foresee any such an explanation.

    I do not see any objection, provided the domain remains large enough to be treated as "infinite".

    Regarding quantum information storage and processing, it should be born in mind that there is no spin polarization for protons in KHCO3. The spin symmetry is a superposition of singlet-like and triplet-like states. Moreover, because proton states are macroscopic, an inevitable consequence of the lattice periodicity, it does not make sense to individualise them as Qbits with definite spin up or down.
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