Fate of the Bose polaron at finite temperature

Abstract

We consider an impurity immersed in a Bose-Einstein condensate with tunable boson-impurity interactions. Such a Bose polaron has recently been predicted to exhibit an intriguing energy spectrum at finite temperature, where the ground-state quasiparticle evenly splits into two branches as the temperature is increased from zero [Guenther et al., Phys. Rev. Lett. 120, 050405 (2018)]. To investigate this theoretical prediction, we employ a recently developed variational approach that systematically includes multi-body correlations between the impurity and the finite-temperature medium, thus allowing us to go beyond previous finite-temperature methods. Crucially, we find that the number of quasiparticle branches is simply set by the number of hole excitations of the thermal cloud, such that including up to one hole yields one splitting, two holes yields two splittings, and so on. Moreover, this effect is independent of the impurity mass. We thus expect that the exact ground-state quasiparticle will evolve into a single broad peak for temperatures $T>0$, with a broadening that scales as $T^{3/4}$ at low temperatures and sufficiently weak boson-boson interactions. In the zero-temperature limit, we show that our calculated ground-state polaron energy is in excellent agreement with recent quantum Monte Carlo results and with experiments.

24 pages, 15 figures

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Cited by in corpus (27)

• Mobile impurity in a Bose-Einstein condensate and the orthogonality catastrophe
• Quantum behavior of a heavy impurity strongly coupled to a Bose gas
• Theory of radio-frequency spectroscopy of impurities in quantum gases
• Quench Dynamics of the Ideal Bose Polaron at Zero and Nonzero Temperatures
• Renormalization group study of Bose polarons
• Pump Probe Spectroscopy of Bose Polarons: Dynamical Formation and Coherence
• Polarons and bipolarons in a two-dimensional square lattice
• Radio-frequency response and contact of impurities in a quantum gas
• Phase diagram for strong-coupling Bose polarons
• Impurity in a three-dimensional unitary Bose gas
• Variational approach to the two-dimensional Bose polaron
• Weakly-interacting Bose-Bose mixtures from the functional renormalisation group
• Polaritons for testing the universality of an impurity in a Bose-Einstein condensate
• Bosonic Functional Determinant Approach and its Application to Polaron Spectra
• Universal quantum dynamics of Bose polarons
• A unified theory of strong coupling Bose polarons: From repulsive polarons to non-Gaussian many-body bound states
• Temperature-induced miscibility of impurities in trapped Bose gases
• Polarons in Binary Bose-Einstein Condensates
• Functional renormalisation group approach to the finite-temperature Bose polaron
• Self-stabilized Bose polarons
• Repulsive Fermi and Bose Polarons in Quantum Gases
• Statistic physics in bound state in 3D fermi gas system
• Polaronic dressing of bound states
• Weak and strong coupling polarons in binary Bose-Einstein condensates
• Phenomenological model of decaying Bose polarons
• Fermi-liquid behaviors in three-dimensional polaron system with tunable dispersion
• Quasiparticle nature of the Bose polaron at finite temperature