Efimov–van der Waals universality for ultracold atoms with positive scattering lengths

Mestrom, P. M. A.; Wang, Jia; Greene, Chris H.; D'Incao, Jose

doi:10.1103/physreva.95.032707

Cited by 34 publications

(52 citation statements)

References 68 publications

(109 reference statements)

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“…The detailed behavior of the interactions at small distances therefore does not play a role. This result has been confirmed in a number of papers, in part also using different methods [38,[42][43][44][45][46][47].…”

Section: Introductionsupporting

confidence: 56%

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

2018

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We calculate the spectrum of three-body Efimov bound states near a Feshbach resonance within a model which accounts both for the finite range of interactions and the presence of background scattering. The latter may be due to direct interactions in an open channel or a second overlapping Feshbach resonance. It is found that background scattering gives rise to substantial changes in the trimer spectrum as a function of the detuning away from a Feshbach resonance, in particular in the regime where the background channel supports Efimov states on its own. Compared to the situation with negligible background scattering, the regime where van der Waals universality applies is shifted to larger values of the resonance strength if the background scattering length is positive. For negative background scattering lengths, in turn, van der Waals universality extends to even small values of the resonance strength parameter, consistent with experimental results on Efimov states in 39 K. Within a simple model, we show that short-range three-body forces do not affect van der Waals universality significantly. Repulsive three-body forces may, however, explain the observed variation between around −8 and −10 of the ratio between the scattering length where the first Efimov trimer appears and the van der Waals length.

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Section: Introductionsupporting

confidence: 56%

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

2018

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“…20. Three-body effective potentials (in van der Waals units) for the BBB (J π = 0 + ) system with atoms interacting via a Lennard-Jones potential tuned to give a = ∞ and no deeply bound states [215][216][217]. The relevant attractive 1 R 2 effective potential for Efimov physics is repulsive for distances R ≲ 2r vdW , preventing atoms from probing the details of the interaction (see inset).…”

Section: B Universality Of the Three-body Parametermentioning

confidence: 99%

“…The results for the relevant three-body parameters obtained from averaging the results of Ref. [217], using a different number of diatomic states, are listed in Table V. The results from Ref.…”

Section: B Universality Of the Three-body Parametermentioning

confidence: 99%

Few-body physics in resonantly interacting ultracold quantum gases

D'Incao

2018

J. Phys. B: At. Mol. Opt. Phys.

144

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We provide a general discussion on the importance of three-body Efimov physics for strongly interacting ultracold quantum gases. Using the adiabatic hyperspherical representation, we discuss a universal classification of three-body systems in terms of the attractive or repulsive character of the effective interactions. The hyperspherical representation leads to a simple and conceptually clear picture for the bound and scattering properties of three-body systems with strong s-wave interactions. Using our universal classification scheme, we present a detailed discussion of all relevant ultracold three-body scattering processes using a pathway analysis that makes evident the importance of Efimov physics in determining the energy and scattering length dependence of such processes. This article provides a general overview of the current status of the field and a discussion of various issues relevant to the lifetime and stability of ultracold quantum gases along with universal properties of ultracold, resonantly interacting, few-body systems.

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“…From the theory side, the universality of the 3BP is predicted to weaken for a > 0 [38][39][40][41][42]. Moreover, it predicts that the first excited Efimov level avoids merging with the atom-dimer continuum due to various finite range effects [41]. Despite continuous theoretical interest, experimental progress is hindered due to inherent limitations of the currently available experimental techniques.In a few previous experiments a limited range of the first excited Efimov energy level has been probed by RF association of distinguishable fermions [43,44] and homonuclear bosons [34].…”

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confidence: 99%

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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Efimov–van der Waals universality for ultracold atoms with positive scattering lengths

Cited by 34 publications

References 68 publications

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

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

Few-body physics in resonantly interacting ultracold quantum gases

Coherent Superposition of Feshbach Dimers and Efimov Trimers

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