Efimov states near a Feshbach resonance and the limits of van der Waals universality at finite background scattering length

Langmack, Christian; Schmidt, Richard; Zwerger, W.

doi:10.1103/physreva.97.033623

Cited by 26 publications

(30 citation statements)

References 83 publications

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“…However, experimental results urged the theory to reinterpret the 3BP. Indeed, it was shown that this universality stems from the fact that atoms interact through a van der Waals potential which suppresses the probability to find the particles at short distances from each other [22][23][24][25][26][27]. The break-down of this universality has been predicted to occur only near closed-channel-dominated Feshbach resonances [28][29][30] which was confirmed in a recent experiment [18].The Efimov-van der Waals universality is well established for a < 0.…”

mentioning

confidence: 81%

Coherent Superposition of Feshbach Dimers and Efimov Trimers

et al. 2019

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A powerful experimental technique to study Efimov physics at positive scattering lengths is demonstrated. We use the Feshbach dimers as a local reference for Efimov trimers by creating a coherent superposition of both states. Measurement of its coherent evolution provides information on the binding energy of the trimers with unprecedented precision and yields access to previously inaccessible parameters of the system such as the Efimov trimers' lifetime and the elastic processes between atoms and the constituents of the superposition state. We develop a comprehensive data analysis suitable for noisy experimental data that confirms the trustworthiness of our demonstration.In few-body physics, the laws of quantum mechanics allow formation of peculiar loosely bound states [1]. Being insensitive to the details of the short range interparticle interactions, they display a variety of universal properties [2]. In recent years ultracold atoms have emerged as a main experimental platform to explore universality in few-body systems [3][4][5]. In the two-body domain, weakly bound dimers are now routinely used for the characterization of Feshbach resonances [6] and serve as the initial state for the production of ultra-cold molecules in their ro-vibrational ground state [7]. In the three-body domain, the captivating subject of Efimov physics has been explored in a variety of atomic systems [8][9][10][11][12][13][14][15][16][17][18]. But, interestingly, experimental techniques used in these explorations have been essentially limited to the study of inter-atomic inelastic processes, such as three-body recombination. Such an approach is best suited for the region of negative scattering lengths (a < 0), where trimers can be associated from the three atom continuum. In contrast, for positive scattering lengths (a > 0) the presence of dimers shifts the recombination related loss features into the atom-dimer continuum and Efimov resonances remain inaccessible for direct observation.One of the central results of experimental research reveals an intriguing universality in the absolute position of the Efimov three-body resonance across diverse openchannel-dominated Feshbach resonances [19] in a variety of atomic species [15,20,21]. The Efimov resonance's position is determined by the three-body parameter (3BP) which has generally been accepted to be system dependent, i.e. sensitive to the short-range physics. However, experimental results urged the theory to reinterpret the 3BP. Indeed, it was shown that this universality stems from the fact that atoms interact through a van der Waals potential which suppresses the probability to find the particles at short distances from each other [22][23][24][25][26][27]. The break-down of this universality has been predicted to occur only near closed-channel-dominated Feshbach resonances [28][29][30] which was confirmed in a recent experiment [18].The Efimov-van der Waals universality is well established for a < 0. However, for a > 0 the situation remains obscure due to the lack of reliable experi...

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confidence: 81%

Coherent Superposition of Feshbach Dimers and Efimov Trimers

et al. 2019

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“…Finally, the interaction of the impurity with the bath of fermions is described by the third term, where the impurityψ σ and a host atomψ are converted into the molecular stateφ. Here the form factor χ(r) determines the shape of the atom-to-molecule coupling and we choose χ(r) = e −r/ρ /4πρ 2 r where the range ρ is determined by the van-der-Waals length [84,85].…”

Section: Anderson-fano Modelmentioning

confidence: 99%

Universal many-body response of heavy impurities coupled to a Fermi sea: a review of recent progress

et al. 2018

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In this report we discuss the dynamical response of heavy quantum impurities immersed in a Fermi gas at zero and at finite temperature. Studying both the frequency and the time domain allows one to identify interaction regimes that are characterized by distinct many-body dynamics. From this theoretical study a picture emerges in which impurity dynamics is universal on essentially all time scales, and where the high-frequency few-body response is related to the long-time dynamics of the Anderson orthogonality catastrophe by Tan relations. Our theoretical description relies on different and complementary approaches: functional determinants give an exact numerical solution for time- and frequency-resolved responses, bosonization provides accurate analytical expressions at low temperatures, and the theory of Toeplitz determinants allows one to analytically predict response up to high temperatures. Using these approaches we predict the thermal decoherence rate of the fermionic system and prove that within the considered model the fastest rate of long-time decoherence is given by [Formula: see text]. We show that Feshbach resonances in cold atomic systems give access to new interaction regimes where quantum effects can prevail even in the thermal regime of many-body dynamics. The key signature of this phenomenon is a crossover between different exponential decay rates of the real-time Ramsey signal. It is shown that the physics of the orthogonality catastrophe is experimentally observable up to temperatures [Formula: see text] where it leaves its fingerprint in a power-law temperature dependence of thermal spectral weight and we review how this phenomenon is related to the physics of heavy ions in liquid [Formula: see text]He and the formation of Fermi polarons. The presented results are in excellent agreement with recent experiments on LiK mixtures, and we predict several new phenomena that can be tested using currently available experimental technology.

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“…Calculations from theories based on a single-channel van der Waals model confirmed this vdW universality for broad Feshbach resonances [26,27,30,41,42]. In recent studies, the observed nonuniversal Efimov ground state locations further confirm that the vdW universality of 3BP is valid only for broad Feshbach resonances [25,43,44]. For heteronuclear systems, i.e.…”

Section: Introductionmentioning

confidence: 66%

Universal three-body parameter of heavy-heavy-light systems with a negative intraspecies scattering length

Zhao

Han

et al. 2019

Phys. Rev. A

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The three-body parameter (3BP) a (1) − is crucial for understanding Efimov physics, and a universal 3BP has been shown in experiments and theory in ultracold homonuclear gases. The 3BP of heteronuclear systems has been predicted to possess much richer properties than its homonuclear counterparts due to the larger parameter space. In this work, we investigate the universal properties of a (1) − for heavy-heavy-light (HHL) systems with a negative intraspecies scattering length a HH . We find that a (1) − follows a universal behavior determined by the van der Waals (vdW) interaction and the mass ratio. A linear fit of a (1) − for large a HH leads to a simple formula, which gives the general dependence of a (1) − on the mass ratio and the vdW length r vdW,HL . In a special case, when the two heavy atoms are in resonance, a (1) − is approximately constant: a (1) − = −(6.3 ± 0.6) r vdW,HL . * huilihan@wipm.ac.cn 1 arXiv:1903.09565v3 [cond-mat.quant-gas]

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Efimov states near a Feshbach resonance and the limits of van der Waals universality at finite background scattering length

Cited by 26 publications

References 83 publications

Coherent Superposition of Feshbach Dimers and Efimov Trimers

Coherent Superposition of Feshbach Dimers and Efimov Trimers

Universal many-body response of heavy impurities coupled to a Fermi sea: a review of recent progress

Universal three-body parameter of heavy-heavy-light systems with a negative intraspecies scattering length

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