Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température
It is generally accepted that the phonon gas of a superfluid always enters a weak coupling regime at sufficiently low temperatures, whatever the strength of the interactions between the underlying particles (constitutive of the superfluid). Thus, in this limit, we should always be able to calculate...
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Académie des sciences
2024-02-01
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| Series: | Comptes Rendus. Physique |
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| Online Access: | https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.169/ |
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| author | Castin, Yvan Serafin, Alan Sinatra, Alice |
| author_facet | Castin, Yvan Serafin, Alan Sinatra, Alice |
| author_sort | Castin, Yvan |
| collection | DOAJ |
| description | It is generally accepted that the phonon gas of a superfluid always enters a weak coupling regime at sufficiently low temperatures, whatever the strength of the interactions between the underlying particles (constitutive of the superfluid). Thus, in this limit, we should always be able to calculate the damping rate of thermal phonons by applying Fermi’s golden rule to the Hamiltonian H3 of cubic phonon-phonon coupling taken from quantum hydrodynamics, at least in the case of a convex acoustic branch and in the collisionless regime (where the eigenfrequency of the considered phonons remains much greater than the gas thermalization rate). Using the many-body Green’s function method, we predict that, unexpectedly, this is not true in two dimensions, contrary to the three-dimensional case. We confirm this prediction with classical phonon-field simulations and a non-perturbative theory in H3, where the fourth order is regularized by hand, giving a complex energy to the virtual phonons of the four-phonon collisional processes. For a weakly interacting fluid and a phonon mode in the long-wavelength limit, we predict a damping rate about three times lower than that of the golden rule. A multilingual version is available in separate files on the open archive HAL at https://hal.science/hal-04168815. |
| format | Article |
| id | doaj-art-cdd265616f894d6682fc7d1b377989c9 |
| institution | Kabale University |
| issn | 1878-1535 |
| language | English |
| publishDate | 2024-02-01 |
| publisher | Académie des sciences |
| record_format | Article |
| series | Comptes Rendus. Physique |
| spelling | doaj-art-cdd265616f894d6682fc7d1b377989c92025-02-07T13:53:11ZengAcadémie des sciencesComptes Rendus. Physique1878-15352024-02-0124S318723910.5802/crphys.16910.5802/crphys.169Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse températureCastin, Yvan0Serafin, Alan1Sinatra, Alice2Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Université Sorbonne et Collège de France, 24 rue Lhomond, 75231 Paris, FranceLaboratoire Kastler Brossel, ENS-Université PSL, CNRS, Université Sorbonne et Collège de France, 24 rue Lhomond, 75231 Paris, FranceLaboratoire Kastler Brossel, ENS-Université PSL, CNRS, Université Sorbonne et Collège de France, 24 rue Lhomond, 75231 Paris, FranceIt is generally accepted that the phonon gas of a superfluid always enters a weak coupling regime at sufficiently low temperatures, whatever the strength of the interactions between the underlying particles (constitutive of the superfluid). Thus, in this limit, we should always be able to calculate the damping rate of thermal phonons by applying Fermi’s golden rule to the Hamiltonian H3 of cubic phonon-phonon coupling taken from quantum hydrodynamics, at least in the case of a convex acoustic branch and in the collisionless regime (where the eigenfrequency of the considered phonons remains much greater than the gas thermalization rate). Using the many-body Green’s function method, we predict that, unexpectedly, this is not true in two dimensions, contrary to the three-dimensional case. We confirm this prediction with classical phonon-field simulations and a non-perturbative theory in H3, where the fourth order is regularized by hand, giving a complex energy to the virtual phonons of the four-phonon collisional processes. For a weakly interacting fluid and a phonon mode in the long-wavelength limit, we predict a damping rate about three times lower than that of the golden rule. A multilingual version is available in separate files on the open archive HAL at https://hal.science/hal-04168815.https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.169/gaz de bosonssuperfluide bidimensionnelgaz d’atomes froidsamortissement Belyaev–Landau des phononsfonctions de Green à N corpshydrodynamique quantique |
| spellingShingle | Castin, Yvan Serafin, Alan Sinatra, Alice Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température Comptes Rendus. Physique gaz de bosons superfluide bidimensionnel gaz d’atomes froids amortissement Belyaev–Landau des phonons fonctions de Green à N corps hydrodynamique quantique |
| title | Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température |
| title_full | Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température |
| title_fullStr | Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température |
| title_full_unstemmed | Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température |
| title_short | Amortissement des phonons dans un superfluide 2D : insuffisance de la règle d’or de Fermi à basse température |
| title_sort | amortissement des phonons dans un superfluide 2d insuffisance de la regle d or de fermi a basse temperature |
| topic | gaz de bosons superfluide bidimensionnel gaz d’atomes froids amortissement Belyaev–Landau des phonons fonctions de Green à N corps hydrodynamique quantique |
| url | https://comptes-rendus.academie-sciences.fr/physique/articles/10.5802/crphys.169/ |
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