<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE article PUBLIC "-//NLM//DTD JATS (Z39.96) Journal Publishing DTD v1.3 20210610//EN" "JATS-journalpublishing1-3.dtd">
<article article-type="research-article" dtd-version="1.3" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xml:lang="en"><front><journal-meta><journal-id journal-id-type="publisher-id">najo</journal-id><journal-title-group><journal-title xml:lang="en">Nanosystems: Physics, Chemistry, Mathematics</journal-title><trans-title-group xml:lang="ru"><trans-title>Наносистемы: физика, химия, математика</trans-title></trans-title-group></journal-title-group><issn pub-type="ppub">2220-8054</issn><issn pub-type="epub">2305-7971</issn><publisher><publisher-name>Университет ИТМО</publisher-name></publisher></journal-meta><article-meta><article-id pub-id-type="doi">10.17586/2220-8054-2015-6-4-501-512</article-id><article-id custom-type="elpub" pub-id-type="custom">najo-1030</article-id><article-categories><subj-group subj-group-type="heading"><subject>Research Article</subject></subj-group><subj-group subj-group-type="section-heading" xml:lang="ru"><subject>Статьи</subject></subj-group></article-categories><title-group><article-title>Exact classical stochastic representations of the many-body quantum dynamics</article-title><trans-title-group xml:lang="ru"><trans-title>Exact classical stochastic representations of the many-body quantum dynamics</trans-title></trans-title-group></title-group><contrib-group><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Polyakov</surname><given-names>E. A.</given-names></name><name name-style="western" xml:lang="en"><surname>Polyakov</surname><given-names>E. A.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Dept. of molecular biophysics and polymer physics, Faculty of Physics</p><p>198504, Saint Petersburg</p></bio><bio xml:lang="en"><p>Dept. of molecular biophysics and polymer physics, Faculty of Physics</p><p>198504, Saint Petersburg</p></bio><email xlink:type="simple">e.a.polyakov@gmail.com</email><xref ref-type="aff" rid="aff-1"/></contrib><contrib contrib-type="author" corresp="yes"><name-alternatives><name name-style="eastern" xml:lang="ru"><surname>Vorontsov-Velyaminov</surname><given-names>P. N.</given-names></name><name name-style="western" xml:lang="en"><surname>Vorontsov-Velyaminov</surname><given-names>P. N.</given-names></name></name-alternatives><bio xml:lang="ru"><p>Dept. of molecular biophysics and polymer physics, Faculty of Physics</p><p>198504, Saint Petersburg</p></bio><bio xml:lang="en"><p>Dept. of molecular biophysics and polymer physics, Faculty of Physics</p><p>198504, Saint Petersburg</p></bio><email xlink:type="simple">voron.wgroup@gmail.com</email><xref ref-type="aff" rid="aff-1"/></contrib></contrib-group><aff-alternatives id="aff-1"><aff xml:lang="ru"><institution>Saint Petersburg State University</institution></aff><aff xml:lang="en"><institution>Saint Petersburg State University</institution></aff></aff-alternatives><pub-date pub-type="collection"><year>2015</year></pub-date><pub-date pub-type="epub"><day>16</day><month>08</month><year>2025</year></pub-date><volume>6</volume><issue>4</issue><fpage>501</fpage><lpage>512</lpage><permissions><copyright-statement>Copyright &amp;#x00A9; Polyakov E.A., Vorontsov-Velyaminov P.N., 2025</copyright-statement><copyright-year>2025</copyright-year><copyright-holder xml:lang="ru">Polyakov E.A., Vorontsov-Velyaminov P.N.</copyright-holder><copyright-holder xml:lang="en">Polyakov E.A., Vorontsov-Velyaminov P.N.</copyright-holder><license xml:lang="ru" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>Данная работа распространяется под лицензией Creative Commons Attribution 4.0.</license-p></license><license xml:lang="en" license-type="creative-commons-attribution" xlink:href="https://creativecommons.org/licenses/by/4.0/" xlink:type="simple"><license-p>This work is licensed under a Creative Commons Attribution 4.0 License.</license-p></license></permissions><self-uri xlink:href="https://nanojournal.ifmo.ru/jour/article/view/1030">https://nanojournal.ifmo.ru/jour/article/view/1030</self-uri><abstract><p>In this work we investigate the exact classical stochastic representations of many-body quantum dynamics. We focus on the representations in which the quantum states and the observables are linearly mapped onto classical quasiprobability distributions and functions in a certain (abstract) phase space. We demonstrate that when such representations have regular mathematical properties, they are reduced to the expansions of the density operator over a certain overcomplete operator basis. Our conclusions are supported by the fact that all the stochastic representations currently known in the literature (quantum mechanics in generalized phase space and, as it recently has been shown by us, the stochastic wave-function methods) have the mathematical structure of the above-mentioned type. We illustrate our considerations by presenting the recently derived operator mappings for the stochastic wave-function method.</p></abstract><trans-abstract xml:lang="ru"><p>In this work we investigate the exact classical stochastic representations of many-body quantum dynamics. We focus on the representations in which the quantum states and the observables are linearly mapped onto classical quasiprobability distributions and functions in a certain (abstract) phase space. We demonstrate that when such representations have regular mathematical properties, they are reduced to the expansions of the density operator over a certain overcomplete operator basis. Our conclusions are supported by the fact that all the stochastic representations currently known in the literature (quantum mechanics in generalized phase space and, as it recently has been shown by us, the stochastic wave-function methods) have the mathematical structure of the above-mentioned type. We illustrate our considerations by presenting the recently derived operator mappings for the stochastic wave-function method.</p></trans-abstract><kwd-group xml:lang="ru"><kwd>quantum ensemble theory</kwd><kwd>quantum noise</kwd><kwd>stochastic equations</kwd></kwd-group><kwd-group xml:lang="en"><kwd>quantum ensemble theory</kwd><kwd>quantum noise</kwd><kwd>stochastic equations</kwd></kwd-group></article-meta></front><back><ref-list><title>References</title><ref id="cit1"><label>1</label><citation-alternatives><mixed-citation xml:lang="ru">Aksenova E. V., Kuz’min V. L., Romanov V. P. Coherent backscattering of light in nematic liquid crystals. J. Exp. Theor. Phys., 2009, 108, P. 516.</mixed-citation><mixed-citation xml:lang="en">Aksenova E. V., Kuz’min V. L., Romanov V. P. Coherent backscattering of light in nematic liquid crystals. J. Exp. Theor. Phys., 2009, 108, P. 516.</mixed-citation></citation-alternatives></ref><ref id="cit2"><label>2</label><citation-alternatives><mixed-citation xml:lang="ru">Aksenova E. V., Kokorin D. I., Romanov V. P. Simulation of coherent backscattering of light in nematic liquid crystals. J. Exp. Theor. Phys., 2012, 115, P. 337.</mixed-citation><mixed-citation xml:lang="en">Aksenova E. V., Kokorin D. I., Romanov V. P. Simulation of coherent backscattering of light in nematic liquid crystals. J. Exp. Theor. Phys., 2012, 115, P. 337.</mixed-citation></citation-alternatives></ref><ref id="cit3"><label>3</label><citation-alternatives><mixed-citation xml:lang="ru">Aksenova E. V., Kokorin D. I., Romanov V. P. Simulation of radiation transfer and coherent backscattering in nematic liquid crystals. Phys. Rev. E., 2014, 89, P. 052506.</mixed-citation><mixed-citation xml:lang="en">Aksenova E. V., Kokorin D. I., Romanov V. P. Simulation of radiation transfer and coherent backscattering in nematic liquid crystals. Phys. Rev. E., 2014, 89, P. 052506.</mixed-citation></citation-alternatives></ref><ref id="cit4"><label>4</label><citation-alternatives><mixed-citation xml:lang="ru">Drummond P. D., Gardiner C. W. Generalized p-representations in quantum optics. J. Phys. A: Math. Gen., 1980, 13, P. 2353.</mixed-citation><mixed-citation xml:lang="en">Drummond P. D., Gardiner C. W. Generalized p-representations in quantum optics. J. Phys. A: Math. Gen., 1980, 13, P. 2353.</mixed-citation></citation-alternatives></ref><ref id="cit5"><label>5</label><citation-alternatives><mixed-citation xml:lang="ru">Deuar P., Drummond P. D. First-principles quantum dynamics in interacting bose gases: I. the positive p representation. J. Phys. A: Math. Gen., 2006, 39, P. 1163.</mixed-citation><mixed-citation xml:lang="en">Deuar P., Drummond P. D. First-principles quantum dynamics in interacting bose gases: I. the positive p representation. J. Phys. A: Math. Gen., 2006, 39, P. 1163.</mixed-citation></citation-alternatives></ref><ref id="cit6"><label>6</label><citation-alternatives><mixed-citation xml:lang="ru">Savage C. M., Schwenn P. E., Kheruntsyan K. V. First-principles quantum simulation of dissociation of molecular condensates: Atom correlations in momentum space. Phys. Rev. A., 2006, 74, P. 033620.</mixed-citation><mixed-citation xml:lang="en">Savage C. M., Schwenn P. E., Kheruntsyan K. V. First-principles quantum simulation of dissociation of molecular condensates: Atom correlations in momentum space. Phys. Rev. A., 2006, 74, P. 033620.</mixed-citation></citation-alternatives></ref><ref id="cit7"><label>7</label><citation-alternatives><mixed-citation xml:lang="ru">Deuar P., Drummond P. D. Correlations in a bec collision: First-principles quantum dynamics with 150 000 atoms. Phys. Rev. Lett., 2007, 98, P. 120402.</mixed-citation><mixed-citation xml:lang="en">Deuar P., Drummond P. D. Correlations in a bec collision: First-principles quantum dynamics with 150 000 atoms. Phys. Rev. Lett., 2007, 98, P. 120402.</mixed-citation></citation-alternatives></ref><ref id="cit8"><label>8</label><citation-alternatives><mixed-citation xml:lang="ru">Juillet O., Gulminelli F. Exact pairing correlations for one-dimensionally trapped fermions with stochastic mean-field wave functions. Phys. Rev. Lett., 2004, 92, P. 160401.</mixed-citation><mixed-citation xml:lang="en">Juillet O., Gulminelli F. Exact pairing correlations for one-dimensionally trapped fermions with stochastic mean-field wave functions. Phys. Rev. Lett., 2004, 92, P. 160401.</mixed-citation></citation-alternatives></ref><ref id="cit9"><label>9</label><citation-alternatives><mixed-citation xml:lang="ru">Biele R., D’Agosta R. A stochastic approach to open quantum systems. J. Phys.: Condens. Matter., 2012, 24, P. 273201.</mixed-citation><mixed-citation xml:lang="en">Biele R., D’Agosta R. A stochastic approach to open quantum systems. J. Phys.: Condens. Matter., 2012, 24, P. 273201.</mixed-citation></citation-alternatives></ref><ref id="cit10"><label>10</label><citation-alternatives><mixed-citation xml:lang="ru">Lee M. D., Ruostekoski J. Classical stochastic measurement trajectories: Bosonic atomic gases in an optical cavity and quantum measurement backaction. Phys. Rev. A., 2014, 90, P. 023628.</mixed-citation><mixed-citation xml:lang="en">Lee M. D., Ruostekoski J. Classical stochastic measurement trajectories: Bosonic atomic gases in an optical cavity and quantum measurement backaction. Phys. Rev. A., 2014, 90, P. 023628.</mixed-citation></citation-alternatives></ref><ref id="cit11"><label>11</label><citation-alternatives><mixed-citation xml:lang="ru">Gardiner C. W., Zoller P. Quantum Noise: a Handbook of Markovian and Non-Markovian Quantum Stochastic Methods with Applications to Quantum Optics. Springer Series in Synergetics. Berlin, Germany, Springer, 2004. ISBN: 3540223010, 9783540223016.</mixed-citation><mixed-citation xml:lang="en">Gardiner C. W., Zoller P. Quantum Noise: a Handbook of Markovian and Non-Markovian Quantum Stochastic Methods with Applications to Quantum Optics. Springer Series in Synergetics. Berlin, Germany, Springer, 2004. ISBN: 3540223010, 9783540223016.</mixed-citation></citation-alternatives></ref><ref id="cit12"><label>12</label><citation-alternatives><mixed-citation xml:lang="ru">Carusotto I., Castin Y. An exact reformulation of the bose-hubbard model in terms of a stochastic gutzwiller ansatz. New. J. Phys., 2003, 5, P. 91.</mixed-citation><mixed-citation xml:lang="en">Carusotto I., Castin Y. An exact reformulation of the bose-hubbard model in terms of a stochastic gutzwiller ansatz. New. J. Phys., 2003, 5, P. 91.</mixed-citation></citation-alternatives></ref><ref id="cit13"><label>13</label><citation-alternatives><mixed-citation xml:lang="ru">Wilkie J. Variational principle for stochastic wave and density equations. Phys. Rev. E., 2003, 67, P. 017102.</mixed-citation><mixed-citation xml:lang="en">Wilkie J. Variational principle for stochastic wave and density equations. Phys. Rev. E., 2003, 67, P. 017102.</mixed-citation></citation-alternatives></ref><ref id="cit14"><label>14</label><citation-alternatives><mixed-citation xml:lang="ru">Tessieri L., Wilkie J., etinba M. Exact norm-preserving stochastic time-dependent hartree-fock. J. Phys. A: Math. Gen., 2005, 38, P. 943.</mixed-citation><mixed-citation xml:lang="en">Tessieri L., Wilkie J., etinba M. Exact norm-preserving stochastic time-dependent hartree-fock. J. Phys. A: Math. Gen., 2005, 38, P. 943.</mixed-citation></citation-alternatives></ref><ref id="cit15"><label>15</label><citation-alternatives><mixed-citation xml:lang="ru">Montina A., Castin Y. Exact bcs stochastic schemes for a time-dependent many-body fermionic system. Phys. Rev. A., 73, P. 013618.</mixed-citation><mixed-citation xml:lang="en">Montina A., Castin Y. Exact bcs stochastic schemes for a time-dependent many-body fermionic system. Phys. Rev. A., 73, P. 013618.</mixed-citation></citation-alternatives></ref><ref id="cit16"><label>16</label><citation-alternatives><mixed-citation xml:lang="ru">Wilkie J., Wong Y. M., Ng R. Survey of exact n-body decompositions of stochastic scalar-jastrow-hartree form. Chem. Phys., 2010, 369, P. 43.</mixed-citation><mixed-citation xml:lang="en">Wilkie J., Wong Y. M., Ng R. Survey of exact n-body decompositions of stochastic scalar-jastrow-hartree form. Chem. Phys., 2010, 369, P. 43.</mixed-citation></citation-alternatives></ref><ref id="cit17"><label>17</label><citation-alternatives><mixed-citation xml:lang="ru">Lacroix D. Stochastic schroedinger equation from optimal observable evolution. Ann. Phys., 2007, 322, P. 2055.</mixed-citation><mixed-citation xml:lang="en">Lacroix D. Stochastic schroedinger equation from optimal observable evolution. Ann. Phys., 2007, 322, P. 2055.</mixed-citation></citation-alternatives></ref><ref id="cit18"><label>18</label><citation-alternatives><mixed-citation xml:lang="ru">Lacroix D. Optimizing stochastic trajectories in exact quantum-jump approaches of interacting systems. Phys. Rev. A., 2005, 72, P. 013805.</mixed-citation><mixed-citation xml:lang="en">Lacroix D. Optimizing stochastic trajectories in exact quantum-jump approaches of interacting systems. Phys. Rev. A., 2005, 72, P. 013805.</mixed-citation></citation-alternatives></ref><ref id="cit19"><label>19</label><citation-alternatives><mixed-citation xml:lang="ru">Breuer H.-P. Exact quantum jump approach to open systems in bosonic and spin baths. Phys. Rev. A., 2004, 69, P. 022115.</mixed-citation><mixed-citation xml:lang="en">Breuer H.-P. Exact quantum jump approach to open systems in bosonic and spin baths. Phys. Rev. A., 2004, 69, P. 022115.</mixed-citation></citation-alternatives></ref><ref id="cit20"><label>20</label><citation-alternatives><mixed-citation xml:lang="ru">Lacroix D., Ayik S. Stochastic quantum dynamics beyond mean field. Eur. Phys. J. A., 2014, 50, P. 95.</mixed-citation><mixed-citation xml:lang="en">Lacroix D., Ayik S. Stochastic quantum dynamics beyond mean field. Eur. Phys. J. A., 2014, 50, P. 95.</mixed-citation></citation-alternatives></ref><ref id="cit21"><label>21</label><citation-alternatives><mixed-citation xml:lang="ru">Polyakov E. A., Vorontsov-Velyaminov P. N. Quasiprobability distributions in stochastic wave-function methods. Phys. Rev. A., 2015, 91, P. 042107.</mixed-citation><mixed-citation xml:lang="en">Polyakov E. A., Vorontsov-Velyaminov P. N. Quasiprobability distributions in stochastic wave-function methods. Phys. Rev. A., 2015, 91, P. 042107.</mixed-citation></citation-alternatives></ref><ref id="cit22"><label>22</label><citation-alternatives><mixed-citation xml:lang="ru">Carusotto I., Castin Y., Dalibard J. N-boson time-dependent problem: A reformulation with stochastic wave functions. Phys. Rev. A., 2001, 63, P. 023606.</mixed-citation><mixed-citation xml:lang="en">Carusotto I., Castin Y., Dalibard J. N-boson time-dependent problem: A reformulation with stochastic wave functions. Phys. Rev. A., 2001, 63, P. 023606.</mixed-citation></citation-alternatives></ref><ref id="cit23"><label>23</label><citation-alternatives><mixed-citation xml:lang="ru">Deuar P., Drummond P. D. Gauge p representations for quantum-dynamical problems: Removal of boundary terms. Phys. Rev. A., 2002, 66, P. 033812.</mixed-citation><mixed-citation xml:lang="en">Deuar P., Drummond P. D. Gauge p representations for quantum-dynamical problems: Removal of boundary terms. Phys. Rev. A., 2002, 66, P. 033812.</mixed-citation></citation-alternatives></ref><ref id="cit24"><label>24</label><citation-alternatives><mixed-citation xml:lang="ru">Corney J. F., Drummond P. D. Gaussian quantum operator representation for bosons. Phys. Rev. A., 2003, 68, P. 063822.</mixed-citation><mixed-citation xml:lang="en">Corney J. F., Drummond P. D. Gaussian quantum operator representation for bosons. Phys. Rev. A., 2003, 68, P. 063822.</mixed-citation></citation-alternatives></ref><ref id="cit25"><label>25</label><citation-alternatives><mixed-citation xml:lang="ru">Corney J. F., Drummond P. D. Gaussian phase-space representations for fermions. Phys. Rev. B., 2006, 73, P. 125112.</mixed-citation><mixed-citation xml:lang="en">Corney J. F., Drummond P. D. Gaussian phase-space representations for fermions. Phys. Rev. B., 2006, 73, P. 125112.</mixed-citation></citation-alternatives></ref><ref id="cit26"><label>26</label><citation-alternatives><mixed-citation xml:lang="ru">Quantum dynamics in ultracold atomic physics / Qiong-Yi He, Margaret D. Reid, Bogdan Opanchuk et al. Front. Phys., 2012, 7, P. 16.</mixed-citation><mixed-citation xml:lang="en">Quantum dynamics in ultracold atomic physics / Qiong-Yi He, Margaret D. Reid, Bogdan Opanchuk et al. Front. Phys., 2012, 7, P. 16.</mixed-citation></citation-alternatives></ref><ref id="cit27"><label>27</label><citation-alternatives><mixed-citation xml:lang="ru">Blaszak M., Doma´nski Z. Phase space quantum mechanics. Ann. Phys. (N. Y.), 2012, 327, P. 167–211.</mixed-citation><mixed-citation xml:lang="en">Blaszak M., Doma´nski Z. Phase space quantum mechanics. Ann. Phys. (N. Y.), 2012, 327, P. 167–211.</mixed-citation></citation-alternatives></ref><ref id="cit28"><label>28</label><citation-alternatives><mixed-citation xml:lang="ru">Gardiner C. Stochastic Methods: A Handbook for the Natural and Social Sciences. Springer Series in Synergetics, Berlin, Germany, Springer, 2009. ISBN: 3540707123, 9783540707127.</mixed-citation><mixed-citation xml:lang="en">Gardiner C. Stochastic Methods: A Handbook for the Natural and Social Sciences. Springer Series in Synergetics, Berlin, Germany, Springer, 2009. ISBN: 3540707123, 9783540707127.</mixed-citation></citation-alternatives></ref><ref id="cit29"><label>29</label><citation-alternatives><mixed-citation xml:lang="ru">Frenkel D., Smit B. Understanding Molecular Simulation. New York : Academic Press, 2001. ISBN: 0122673514, 9780122673511.</mixed-citation><mixed-citation xml:lang="en">Frenkel D., Smit B. Understanding Molecular Simulation. New York : Academic Press, 2001. ISBN: 0122673514, 9780122673511.</mixed-citation></citation-alternatives></ref><ref id="cit30"><label>30</label><citation-alternatives><mixed-citation xml:lang="ru">Cahill K. E., Glauber R. J. Ordered expansions in boson amplitude operators. Phys. Rev., 1969, 177, P. 1857.</mixed-citation><mixed-citation xml:lang="en">Cahill K. E., Glauber R. J. Ordered expansions in boson amplitude operators. Phys. Rev., 1969, 177, P. 1857.</mixed-citation></citation-alternatives></ref><ref id="cit31"><label>31</label><citation-alternatives><mixed-citation xml:lang="ru">Cahill K. E., Glauber R. J. Density operators and quasiprobability distributions. Phys. Rev., 1969, 177, P. 1882.</mixed-citation><mixed-citation xml:lang="en">Cahill K. E., Glauber R. J. Density operators and quasiprobability distributions. Phys. Rev., 1969, 177, P. 1882.</mixed-citation></citation-alternatives></ref><ref id="cit32"><label>32</label><citation-alternatives><mixed-citation xml:lang="ru">Cahill K. E., Glauber R. J. Density operators for fermions. 1999, 59, P. 1538.</mixed-citation><mixed-citation xml:lang="en">Cahill K. E., Glauber R. J. Density operators for fermions. 1999, 59, P. 1538.</mixed-citation></citation-alternatives></ref><ref id="cit33"><label>33</label><citation-alternatives><mixed-citation xml:lang="ru">Gilchrist A., Gardiner C. W., Drummond P. D. Positive p representation: Application and validity. Phys. Rev. A., 1997, 55, P. 3014.</mixed-citation><mixed-citation xml:lang="en">Gilchrist A., Gardiner C. W., Drummond P. D. Positive p representation: Application and validity. Phys. Rev. A., 1997, 55, P. 3014.</mixed-citation></citation-alternatives></ref><ref id="cit34"><label>34</label><citation-alternatives><mixed-citation xml:lang="ru">Juillet O., Chomaz P. Exact stochastic mean-field approach to the fermionic many-body problem. Phys. Rev. Lett., 2002, 88, P. 142503.</mixed-citation><mixed-citation xml:lang="en">Juillet O., Chomaz P. Exact stochastic mean-field approach to the fermionic many-body problem. Phys. Rev. Lett., 2002, 88, P. 142503.</mixed-citation></citation-alternatives></ref><ref id="cit35"><label>35</label><citation-alternatives><mixed-citation xml:lang="ru">Carusotto I., Castin Y. Exact reformulation of the bosonic many-body problem in terms of stochastic wave functions: an elementary derivation. Ann. Henri Poincar´e, 2003, 4, P. S783.</mixed-citation><mixed-citation xml:lang="en">Carusotto I., Castin Y. Exact reformulation of the bosonic many-body problem in terms of stochastic wave functions: an elementary derivation. Ann. Henri Poincar´e, 2003, 4, P. S783.</mixed-citation></citation-alternatives></ref><ref id="cit36"><label>36</label><citation-alternatives><mixed-citation xml:lang="ru">Breuer H.-P. The non-markovian quantum behaviour of open systems: An exact monte carlo method employing stochastic product states. Eur. Phys. J. D., 2004, 29, P. 105.</mixed-citation><mixed-citation xml:lang="en">Breuer H.-P. The non-markovian quantum behaviour of open systems: An exact monte carlo method employing stochastic product states. Eur. Phys. J. D., 2004, 29, P. 105.</mixed-citation></citation-alternatives></ref></ref-list><fn-group><fn fn-type="conflict"><p>The authors declare that there are no conflicts of interest present.</p></fn></fn-group></back></article>
