Landau Effective Interaction between Quasiparticles in a Bose-Einstein Condensate

Abstract

Landau's description of the excitations in a macroscopic system in terms of quasiparticles stands out as one of the highlights in quantum physics. It provides an accurate description of otherwise prohibitively complex many-body systems, and has led to the development of several key technologies. In this paper, we investigate theoretically the Landau effective interaction between quasiparticles, so-called Bose polarons, formed by impurity particles immersed in a Bose-Einstein condensate (BEC). In the limit of weak interactions between the impurities and the BEC, we derive rigorous results for the effective interaction. They show that it can be strong even for weak impurity-boson interaction, if the transferred momentum/energy between the quasiparticles is resonant with a sound mode in the BEC. We then develop a diagrammatic scheme to calculate the effective interaction for arbitrary coupling strengths, which recovers the correct weak coupling results. Using this, we show that the Landau effective interaction in general is significantly stronger than that between quasiparticles in a Fermi gas, mainly because a BEC is more compressible than a Fermi gas. The interaction is particularly large near the unitarity limit of the impurity-boson scattering, or when the quasiparticle momentum is close to the threshold for momentum relaxation in the BEC. Finally, we show how the Landau effective interaction leads to a sizeable shift of the quasiparticle energy with increasing impurity concentration, which should be detectable with present day experimental techniques.

12 pages

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Cited by in corpus (60)

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• Stability and breakdown of Fermi polarons in a strongly interacting Fermi-Bose mixture
• Repulsive Fermi Polarons and Their Induced Interactions in Binary Mixtures of Ultracold Atoms
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• Interactions mediated by atoms, photons, electrons, and excitons
• Polarons and bipolarons in a two-dimensional square lattice
• Polariton dynamics in strongly interacting quantum many-body systems
• Induced interactions and quench dynamics of bosonic impurities immersed in a Fermi sea
• Counterflow dynamics of two correlated impurities immersed in a bosonic gas
• Ground state properties of interacting Bose polarons
• Strongly interacting Bose-Fermi mixture: mediated interaction, phase diagram and sound propagation
• Crossover from attractive to repulsive induced interactions and bound states of two distinguishable Bose polarons
• Mobile impurities interacting with a few one-dimensional lattice bosons
• Exploring emergent heterogeneous phases in strongly repulsive Fermi gases
• Medium-induced Interaction Between Impurities in a Bose-Einstein Condensate
• Collective excitations of a Bose-Einstein condensate of hard-core bosons and their mediated interactions: from two-body bound states to mediated superfluidity
• Compound atom-ion Josephson junction: Effects of finite temperature and ion motion
• A mobile ion in a Fermi sea
• Nonlinear optical response of resonantly driven polaron-polaritons
• Polaritons in an electron gas -- quasiparticles and Landau effective interactions
• Engineering impurity Bell states through coupling with a quantum bath
• Superfluid flow of polaron polaritons above Landau's critical velocity
• Ion-induced interactions in a Tomonaga-Luttinger liquid
• Polarizing the Medium: Fermion-Mediated Interactions between Bosons
• Weakly-interacting Bose-Bose mixtures from the functional renormalisation group
• Lattice Bose polarons at strong coupling and quantum criticality
• Strong connection between single-particle and density excitations in Bose-Einstein condensates
• The cross-over from Townes solitons to droplets in a 2D Bose mixture
• Polaritons for testing the universality of an impurity in a Bose-Einstein condensate
• Universal quantum dynamics of Bose polarons
• BCS-BCS crossover between atomic and molecular superfluids in a Bose-Fermi mixture
• Effective approaches to the dynamical properties of two distinguishable Bose polarons
• Mediated Interactions and Damping Effects in Superfluid Mixtures of Bose and Fermi Gases
• Spin-charge bound states and emerging fermions in a quantum spin liquid
• Repulsive Fermi and Bose Polarons in Quantum Gases
• Medium-enhanced polaron repulsion in a dilute Bose mixture
• Tunable Fujita-Miyazawa-Type Three-Body Force in Ultracold Atoms
• Polaronic dressing of bound states
• Effective two- and three-body interactions between dressed impurities in a tilted double-well potential
• Complex-valued in-medium potential between heavy impurities in ultracold atoms