Observation of Massless and Massive Collective Excitations with Faraday Patterns in a Two-Component Superfluid

Cominotti, Riccardo; Berti, Anna; Farolfi, A.; Zenesini, Alessandro; Lamporesi, Giacomo; Carusotto, Iacopo; Recati, Alessio; Ferrari, G.

doi:10.1103/physrevlett.128.210401

Cited by 31 publications

(28 citation statements)

References 37 publications

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“…In this work, we generalize polaron problems from a single component boson bath to a binary bath. Binary interacting BECs have two kinds of collective excitation, the density branch and spin branch [21][22][23][24][25], compare to a single component BEC that has only one kind of excitation. Furthermore, Binary BECs due to their multiple tunable interactions and other parameters can manifest significant features such as phase separation and the droplet phase, which does not occur in the case of a single bath.…”

Section: Introductionmentioning

confidence: 99%

Polarons in Binary Bose-Einstein Condensates

Liu¹,

Tu²

2022

Preprint

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Impurities coupled with collective excitations of Bose-Einstein condensates lead to the emergence of Bose polarons. In this paper, we investigate the properties of a single impurity immersed in binary Bose-Einstein condensates in the framework of the Lee-Low-Pines variational approach.We derive an effective Fröhlich Hamiltonian with two kinds of effective impurity-phonon interactions, i.e., the interactions of the impurity-density branch and impurity-spin branch. The stability criterion against phase separation limits the impurity-spin branch's behavior. We show that the Bose polaron in a small momentum has explicit analytical results in single and interacting binary baths. In the case of bosons with equal mass, we find the polaron properties are proportional or inversely proportional to √ a +(−) , a +(−) is a reduced scattering length of density branch (+) and spin branch (−). Whereas in the case of unequal mass bosons, we illustrate that the density and spin branch can transform each other via a permutation of mass of two kinds of bosons. These integral results provide fundamental understandings of behaviors of polarons in Bose baths with multiple components.

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Section: Introductionmentioning

confidence: 99%

Polarons in Binary Bose-Einstein Condensates

Liu¹,

Tu²

2022

Preprint

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“…In this perspective, ultracold atomic gases have opened a new path for the investigation of such many-body problems, especially thanks to the precise control of interactions [3][4][5][6][7][8][9]. In the case of miscible Bose mixtures with two spin components, the dispersion relations of density and spin linear excitations have been studied experimentally [10,11], as well as the nonlinear excitations known as magnetic solitons [12,13]. The superfluid character of the spin degree of freedom was also demonstrated by observing undamped spin-dipole oscillations [14] and by moving a magnetic obstacle [15] in such a mixture.…”

Section: Introductionmentioning

confidence: 99%

“…The superfluid character of the spin degree of freedom was also demonstrated by observing undamped spin-dipole oscillations [14] and by moving a magnetic obstacle [15] in such a mixture. Moreover, it has been shown that a coherent coupling between the two components-with or without momentum transfer-can modify the bare dispersion relations in a controlled manner [11], induce spin-orbit coupling to produce a variety of quantum phases [16], and trigger dynamical instabilities [17].…”

Section: Introductionmentioning

confidence: 99%

The cross-over from Townes solitons to droplets in a 2D Bose mixture

et al. 2023

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When two Bose-Einstein condensates – labelled 1 and 2 – overlap spatially, the equilibrium state of the system depends on the miscibility criterion for the two fluids. Here, we theoretically focus on the non-miscible regime in two spatial dimensions and explore the properties of the localized wave packet formed by the minority component 2 when immersed in an infinite bath formed by component 1. We address the zero-temperature regime and describe the two-fluid system by coupled classical field equations. We show that such a wave packet exists only for an atom number N 2 above a threshold value corresponding to the Townes soliton state. We identify the regimes where this localized state can be described by an effective single-field equation up to the droplet case, where component 2 behaves like an incompressible fluid. We study the near-equilibrium dynamics of the coupled fluids, which reveals specific parameter ranges for the existence of localized excitation modes.

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“…This must be associated to a high stability and accuracy of the tuning parameters. An extended ferromagnetic superfluid [27] possesses the ideal properties to act as a field simulator, in particular its first order phase transition character, the long range coherence and the flexibility to control its experimental parameters within a stable and isolated environment. In tight analogy with supercooling, in an extended quantum system the presence of a spatial region with different magnetization to the bulk carries a positive kinetic energy due to the winding of the field at the interface, see Fig.…”

mentioning

confidence: 99%

Observation of false vacuum decay via bubble formation in ferromagnetic superfluids

Berti

Cominotti

Rogora

et al. 2023

Preprint

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Metastability is ubiquitous in nature and is observed through the crossing of an energy barrier toward a configuration of lower energy as, for example, in chemical processes [1] or electron field ionization [2]. In classical many-body systems, metastability naturally emerges in the presence of a first-order phase transition and finds a prototypical example in supercooled vapour. In the last decades, the extension to quantum field theory and quantum many-body systems has attracted significant interest in the context of statistical physics [3, 4], protein folding [5, 6], and cosmology [7–9], where thermal and quantum fluctuations are expected to trigger the transition from the metastable state (false vacuum) to the ground state (real vacuum) via the probabilistic nucleation of spatially localized bubbles [10, 11]. However, the long-standing theoretical progress in estimating the relaxation rate of the metastable field via bubble nucleation has not yet found a counterpart in terms of experimental observations. Here we experimentally observe and characterize bubble nucleation in isolated and coherently-coupled atomic superfluids, and support our observations with numerical simulations. The agreement between our results and a novel analytic formula based on instanton theory confirms the quantum-field character of the observed decay, and promotes coherently-coupled atomic superfluids as emulators of out-of-equilibrium quantum field phenomena.

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Observation of Massless and Massive Collective Excitations with Faraday Patterns in a Two-Component Superfluid

Cited by 31 publications

References 37 publications

Polarons in Binary Bose-Einstein Condensates

Polarons in Binary Bose-Einstein Condensates

The cross-over from Townes solitons to droplets in a 2D Bose mixture

Observation of false vacuum decay via bubble formation in ferromagnetic superfluids

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