A smooth polaron–molecule crossover in a Fermi system

Edwards, D. M.

doi:10.1088/0953-8984/25/42/425602

Cited by 13 publications

(11 citation statements)

References 26 publications

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“…This naturally resolves the theoretical debate in Ref. [35] because the transition is between different Q-states rather than between different forms of variational ansatz. Furthermore, near the transition point, we found the double-minima (at |Q| = 0 and k F ) structure of the impurity dispersion curve, providing the underlying mechanism for polaron-molecule coexistence in realistic systems.…”

Section: Introductionsupporting

confidence: 64%

“…As a result, the conclusion of polaronmolecule transition can easily get questioned. For instance, a previous theory [35] claimed the absence of such transition by showing that the two types of variational ansatz are mutually contained in a generalized momentum space if more p-h excitations are included. Therefore, the relation and competition between polaron and molecule deserve a close re-examination under a unified framework.…”

Section: Introductionmentioning

confidence: 99%

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Nature of polaron-molecule transition in Fermi polarons

Peng,

Liu,

Zhang

et al. 2021

Preprint

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Section: Introductionsupporting

confidence: 64%

Section: Introductionmentioning

confidence: 99%

Nature of polaron-molecule transition in Fermi polarons

Peng,

Liu,

Zhang

et al. 2021

Preprint

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“…It was predicted that the energies of the polaron and molecular states cross around ðk F aÞ −1 c ≈ 0.9-with k F being the Fermi wave vector of the majority-leading to a sharp, first-order transition between the two ground states [27,29,[37][38][39][40]. Contrasting claims for a smooth crossover were also put forward [41][42][43][44].…”

Section: Introductionmentioning

confidence: 99%

Observation of a Smooth Polaron-Molecule Transition in a Degenerate Fermi Gas

et al. 2020

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Understanding the behavior of an impurity strongly interacting with a Fermi sea is a long-standing challenge in many-body physics. When the interactions are short ranged, two vastly different ground states exist: a polaron quasiparticle and a molecule dressed by the majority atoms. In the single-impurity limit, it is predicted that at a critical interaction strength, a first-order transition occurs between these two states. Experiments, however, are always conducted in the finite temperature and impurity density regime. The fate of the polaron-to-molecule transition under these conditions, where the statistics of quantum impurities and thermal effects become relevant, is still unknown. Here, we address this question experimentally and theoretically. Our experiments are performed with a spin-imbalanced ultracold Fermi gas with tunable interactions. Utilizing a novel Raman spectroscopy combined with a high-sensitivity fluorescence detection technique, we isolate the quasiparticle contribution and extract the polaron energy, spectral weight, and the contact parameter. As the interaction strength is increased, we observe a continuous variation of all observables, in particular a smooth reduction of the quasiparticle weight as it goes to zero beyond the transition point. Our observation is in good agreement with a theoretical model where polaron and molecule quasiparticle states are thermally occupied according to their quantum statistics. At the experimental conditions, polaron states are hence populated even at interactions where the molecule is the ground state and vice versa. The emerging physical picture is thus that of a smooth transition between polarons and molecules and a coexistence of both in the region around the expected transition. Our findings establish Raman spectroscopy as a powerful experimental tool for probing the physics of mobile quantum impurities and shed new light on the competition between emerging fermionic and bosonic quasiparticles in non-Fermi-liquid phases.

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“…Note that if we follow the lower spectral feature, we see a "molecule-to-polaron transition", in the sense that, for µ E b , the single particle spectrum is fully incoherent, but fully coherent in the opposite limit. However, the details of this transition/crossover [58] remain to be explored. In particular, it would be interesting to analyze this in 3D, where a bound state only forms at a certain strength of the interparticle attraction.…”

mentioning

confidence: 99%

Spectra of heavy polarons and molecules coupled to a Fermi sea

Pimenov¹,

Goldstein

2018

Phys. Rev. B

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We study the spectrum of an impurity coupled to a Fermi sea (e.g., minority atom in an ultracold gas, exciton in a solid) by attraction strong enough to form a molecule/trion. We introduce a diagrammatic scheme which allows treating a finite mass impurity while reproducing the Fermi edge singularity in the immobile limit. For large binding energies the spectrum is characterized by a semicoherent repulsive polaron and an incoherent molecule-hole continuum, which is the lowest-energy feature in the single-particle spectrum. The previously predicted attractive polaron seems not to exist for strong binding. arXiv:1809.02577v2 [cond-mat.str-el]

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A smooth polaron–molecule crossover in a Fermi system

Cited by 13 publications

References 26 publications

Nature of polaron-molecule transition in Fermi polarons

Nature of polaron-molecule transition in Fermi polarons

Observation of a Smooth Polaron-Molecule Transition in a Degenerate Fermi Gas

Spectra of heavy polarons and molecules coupled to a Fermi sea

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