Self-trapping of impurities in Bose-Einstein condensates: Strong attractive and repulsive coupling

Bruderer, M.; Bao, Weizhu; Jaksch, Dieter

doi:10.1209/0295-5075/82/30004

Cited by 95 publications

(126 citation statements)

References 33 publications

(61 reference statements)

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“…Important generalizations of the Fröhlich Hamiltonian include the Holstein model on a lattice [7], electrons coupled to acoustical phonons in a crystal [8], and, more recently, impurity particles immersed in a dilute Bose-Einstein condensate (BEC) gas [9][10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…However, so far, there have been no studies exploiting Feshbach resonances to increase the strength of interspecies interactions or measuring basic polaron properties such as their binding energy, lifetime, and effective mass. On the theoretical side, the self-localization of Bose polarons was investigated using mean-field approaches [9][10][11]21,22] as well as Feynman's variational method applied to the effective Hamiltonian describing the impurity [12,23]. Starting from the Fröhlich Hamiltonian other studies have focused on the calculation of the radio-frequency response of the polaron [24] and of its binding energy and effective mass using renormalization-group [25] and diagrammatic Monte Carlo [26] methods.…”

Section: Introductionmentioning

confidence: 99%

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Impurity in a Bose-Einstein condensate: Study of the attractive and repulsive branch using quantum Monte Carlo methods

2015

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We investigate the properties of an impurity immersed in a dilute Bose gas at zero temperature using quantum Monte Carlo methods. The interactions between bosons are modeled by a hard-sphere potential with scattering length a, whereas the interactions between the impurity and the bosons are modeled by a short-range, square-well potential where both the sign and the strength of the scattering length b can be varied by adjusting the well depth. We characterize the attractive and the repulsive polaron branch by calculating the binding energy and the effective mass of the impurity. Furthermore, we investigate the structural properties of the bath, such as the impurity-boson contact parameter and the change of the density profile around the impurity. At the unitary limit of the impurity-boson interaction, we find that the effective mass of the impurity remains smaller than twice its bare mass, while the binding energy scales with 2 n 2/3 /m, where n is the density of the bath and m is the common mass of the impurity and the bosons in the bath. The implications for the phase diagram of binary Bose-Bose mixtures at low concentrations are also discussed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Impurity in a Bose-Einstein condensate: Study of the attractive and repulsive branch using quantum Monte Carlo methods

2015

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“…Lots of theoretical efforts have been paid to study the Fermi polaron [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and the Bose polaron [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. Nearby a Feshbach resonance, a Fermi polaron displays an attractive branch [20][21][22][23][24][25]29] and a repulsive branch [26][27][28], which directly manifests two-body correlations in this system.…”

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confidence: 99%

Visualizing the Efimov Correlation in Bose Polarons

2017

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The Bose polaron is a quasi-particle of an impurity dressed by surrounding bosons. In fewbody physics, it is known that two identical bosons and a third distinguishable particle can form a sequence of Efimov bound states in the vicinity of inter-species scattering resonance. On the other hand, in the Bose polaron system with an impurity atom embedded in many bosons, no signature of Efimov physics has been reported in the existing spectroscopy measurements up to date. In this work, we propose that a large mass imbalance between a light impurity and heavy bosons can help produce visible signatures of Efimov physics in such a spectroscopy measurement. Using the diagrammatic approach in the Virial expansion to include three-body effects from pairwise interactions, we determine the impurity self-energy and its spectral function. Taking 6 Li-133 Cs system as a concrete example, we find two visible Efimov branches in the polaron spectrum, as well as their hybridizations with the attractive polaron branch. We also discuss the general scenarios for observing the signature of Efimov physics in polaron systems. This work paves the way for experimentally exploring intriguing few-body correlations in a many-body system in the near future.Top-down and bottom-up are two major approaches to studying correlations in a quantum many-body system. The cold atom system has intrinsic advantage for the bottom-up approach since it is a dilute system and the few-body problems therein are well understood. In this approach, one would like to understand how manybody physics is built up from few-body correlations. In cold atom system, one of the most intriguing three-body correlations lies in Efimov physics, which is characterized by an infinite number of trimer states nearby a two-body resonance and following a universal scaling law [1,2]. Efimov physics has been observed in a number of cold atoms experiments, while all of them are at the few-body level [3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19]. The manifestation of Efimov physics in the many-body system has yet to be observed.In this context, a convenient and non-trivial testbed is the highly-polarized ultracold gases, which consist of minority impurity atoms interacting with the majority of fermionic or bosonic atoms, respectively called the Fermi or the Bose polarons. Lots of theoretical efforts have been paid to study the Fermi polaron [20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35] and the Bose polaron [36][37][38][39][40][41][42][43][44][45][46][47][48][49][50][51]. Nearby a Feshbach resonance, a Fermi polaron displays an attractive branch [20][21][22][23][24][25]29] and a repulsive branch [26][27][28], which directly manifests two-body correlations in this system. In the past few years, the Fermi polaron has been studied by a number of experiments [52][53][54][55][56][57], while the Bose polaron has only recently been explored [58][59][60]. Most of these experiments are the injection radio-frequency spectroscopy measurements, with which both the r...

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“…This pursuit requires theoretical models for describing the Bose polaron [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], where, in contrast to the Fermi polaron, an exact solution is not known even for a homogeneous 1D system. Here we provide a new theoretical framework that captures the properties of an impurity in a bosonic bath confined in one spatial dimension.…”

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confidence: 99%

Quantum impurity in a one-dimensional trapped Bose gas

2015

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We present a new theoretical framework for describing an impurity in a trapped Bose system in one spatial dimension. The theory handles any external confinement, arbitrary mass ratios, and a weak interaction may be included between the Bose particles. To demonstrate our technique, we calculate the ground state energy and properties of a sample system with eight bosons and find an excellent agreement with numerically exact results. Our theory can thus provide definite predictions for experiments in cold atomic gases.PACS numbers: 03.75. Mn,67.85.Pq An impurity interacting with a reservoir of quantum particles is an essential problem of fundamental physics. Famous examples include a single charge in a polarizable environment, the Landau-Pekar polaron [1, 2], a neutral particle in superfluid 4 He [3], a magnetic impurity in a metal resulting in the Kondo effect [4], and a single scattering potential inside an ideal Fermi gas [5,6]. The latter system is famous for the Anderson's orthogonality catastrophe [7]. In these settings the impurity behavior can provide key insights into the many-body physics and guide our understanding of more general setups.A complicating feature of many impurity problems is the presence of interactions at a level that often precludes the use of perturbative analysis and self-consistent mean-field approximations. This implies that analytical approaches are highly desirable and exact solutions are, when available, coveted tools for benchmarking other techniques. This is particularly true for one-dimensional (1D) homogeneous systems where solutions can often be found based on the Bethe ansatz [8][9][10][11][12][13]. These solutions are the essential ingredients for our analytical understanding of highly controllable experiments with cold atoms [14][15][16][17][18][19]. For instance, the exactly solvable problem of the single impurity in a 1D Fermi sea [10] -the Fermi polaron -can be used to study the atom-by-atom formation of a 1D Fermi sea [20].While Fermi polarons have been studied intensively in recent times using cold atomic setups both experimentally and theoretically [21][22][23][24][25], the physics of impurities in a bosonic environment is only now becoming a frontier in cold atom experiments [26][27][28][29]. This pursuit requires theoretical models for describing the Bose polaron [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48], where, in contrast to the Fermi polaron, an exact solution is not known even for a homogeneous 1D system. Here we provide a new theoretical framework that captures the properties of an impurity in a bosonic bath confined in one spatial dimension. Our (semi)-analytical theory thus provides a state-of-the-art tool for exploring the properties of Bose polarons in 1D.The proposed framework works with a zero-range potential of any strength and handles any number of ma- FIG. 1: (color online) a)A sketch of the doubly-degenerate ground state for the system of one A and eight B particles trapped in a one-dimensional harmonic potential ...

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Self-trapping of impurities in Bose-Einstein condensates: Strong attractive and repulsive coupling

Cited by 95 publications

References 33 publications

Impurity in a Bose-Einstein condensate: Study of the attractive and repulsive branch using quantum Monte Carlo methods

Impurity in a Bose-Einstein condensate: Study of the attractive and repulsive branch using quantum Monte Carlo methods

Visualizing the Efimov Correlation in Bose Polarons

Quantum impurity in a one-dimensional trapped Bose gas

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