Low-energy effective theory of non-thermal fixed points in a multicomponent Bose gas

• Verfasst von: Mikheev, Aleksandr N. [VerfasserIn]
• Verfasst von: Schmied, Christian-Marcel [VerfasserIn]
• Verfasst von: Gasenzer, Thomas [VerfasserIn]
• Titel: Low-energy effective theory of non-thermal fixed points in a multicomponent Bose gas
• Verf.angabe: Aleksandr N. Mikheev, Christian-Marcel Schmied, and Thomas Gasenzer
• E-Jahr: 2018
• Jahr: 26 Jul 2018
• Umfang: 27 S.
• Fussnoten: Gesehen am 19.11.2020 ; Last revised 16 Sep 2019
• Titel Quelle: Enthalten in: De.arxiv.org
• Ort Quelle: [S.l.] : Arxiv.org, 1991
• Jahr Quelle: 2018
• Band/Heft Quelle: (2018) Artikel-Nummer 1807.10228, 27 Seiten
• Datenträger: Online-Ressource
• Sprache: eng
• Sach-SW: High Energy Physics - Phenomenology
• Sach-SW: Condensed Matter - Quantum Gases
• Sach-SW: Condensed Matter - Statistical Mechanics
• K10plus-PPN: 1586379887

Abstract

Non-thermal fixed points in the evolution of a quantum many-body system quenched far out of equilibrium manifest themselves in a scaling evolution of correlations in space and time. We develop a low-energy effective theory of non-thermal fixed points in a bosonic quantum many-body system by integrating out long-wave-length density fluctuations. The system consists of $N$ distinguishable spatially uniform Bose gases with $O(N)\times U(1)$-symmetric interactions. The effective theory describes interacting Goldstone modes of the total and relative-phase excitations. It is similar in character to the non-linear Luttinger-liquid description of low-energy phonons in a single dilute Bose gas, with the markable difference of a universal non-local coupling function depending, in the large-$N$ limit, only on momentum, single-particle mass, and density of the gas. Our theory provides a perturbative description of the non-thermal fixed point, technically easy to apply to experimentally relevant cases with a small number of fields $N$. Numerical results for $N=3$ allow us to characterize the analytical form of the scaling function and confirm the analytically predicted scaling exponents. The fixed point which is dominated by the relative phases is found to be Gaussian, while a non-Gaussian fixed point is anticipated to require scaling evolution with a distinctly lower power of time.