From Efimov Physics to the Bose Polaron using Gaussian States

Abstract

Since the Efimov effect was introduced in 1970, a detailed theoretical understanding of Efimov physics has been developed in the few-body context. However, it has proven to be challenging to describe the role Efimov-type correlations play in many-body systems such as quenched or collapsing Bose-Einstein condensates (BECs). To study the impact the Efimov effect can have in such scenarios, we consider a light impurity immersed in a weakly interacting BEC, forming a Bose polaron. In this case, the higher-order correlations are localized around the impurity, making it more feasible to develop a theoretical description. Specifically, we employ a Gaussian state variational Ansatz in the reference frame of the impurity, capable of both capturing the Efimov effect and the formation of the polaron cloud. We find that the Efimov effect leads to a cooperative binding of bosons to the impurity and the formation of a many-body bound state. As a result, the polaron is not the ground state, but rendered a metastable excited state which can decay into these Efimov clusters. While this decay is slow for small interaction strengths, it becomes more prominent as the attractive scattering length increases, up to the point where the polaron becomes completely unstable. This critical scattering length can be interpreted as a many-body shifted Efimov resonance, where the scattering of two excitations of the bath with the polaron can lead to bound state formation. Compared to the few-body case, the resonance is shifted to smaller attractive scattering lengths due to the participation of the polaron cloud in the cooperative binding process. This corresponds to an intriguing scenario of polaron-assisted chemistry, where many-body effects lead to enhanced signal of the chemical recombination process, which can be directly probed in state-of-the-art experiments.

20 pages, 9 figures

References in corpus (12)

• Observation of Fermi Polarons in a Tunable Fermi Liquid of Ultracold Atoms
• Evidence for Universal Four-Body States Tied to an Efimov Trimer
• Observation of Efimov Resonances in a Mixture with Extreme Mass Imbalance
• Rotation of quantum impurities in the presence of a many-body environment
• Quasiparticle approach to molecules interacting with quantum solvents
• Heteronuclear Efimov scenario with positive intraspecies scattering length
• Breathing Mode of a BEC Repulsively Interacting with a Fermionic Reservoir
• Bose-Einstein condensation of Efimovian triples in the unitary Bose gas
• Universality in Efimov associated tetramers in 4He
• Quench Dynamics of the Ideal Bose Polaron at Zero and Nonzero Temperatures
• Enhancing the Efimov correlation in Bose polarons with large mass imbalance
• Chemistry of a light impurity in a Bose-Einstein condensate

Cited by in corpus (22)

• Quantum mixtures of ultracold gases of neutral atoms
• Life and death of the Bose polaron
• Chemistry of a light impurity in a Bose-Einstein condensate
• Phase diagram for strong-coupling Bose polarons
• Variational approach to the two-dimensional Bose polaron
• Fast quantum state preparation and bath dynamics using non-Gaussian variational ansatz and quantum optimal control
• Interferometry of Efimov states in thermal gases by modulated magnetic fields
• Open quantum dynamics with variational non-Gaussian states and the truncated Wigner approximation
• Universal quantum dynamics of Bose polarons
• Observation of a Halo Trimer in an Ultracold Bose-Fermi Mixture
• Bosonic Functional Determinant Approach and its Application to Polaron Spectra
• Polaritons for testing the universality of an impurity in a Bose-Einstein condensate
• Resonance triplet dynamics in the quenched unitary Bose gas
• 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
• Role of Matter Interactions in Superradiant Phenomena
• Polaron catastrophe within quantum acoustics
• Functional renormalisation group approach to the finite-temperature Bose polaron
• Non-equilibrium dynamics and atom-pair coherence in strongly interacting Bose-Fermi mixtures
• Medium-enhanced polaron repulsion in a dilute Bose mixture
• Polaronic dressing of bound states
• Competition of light- and phonon-dressing in microwave-dressed Bose polarons