Excitonic states of an impurity in a Fermi gas

Lan, Zhihao; Lobo, Carlos

doi:10.1103/physreva.92.053605

Cited by 4 publications

(2 citation statements)

References 33 publications

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“…The above experiments have also energized theoretical investigations, which include various issues of atomic polarons in zero-temperature media: quasiparticle properties of Bose polarons [20][21][22][23][24][25][26][27][28][29][30] and Fermi polarons [31][32][33][34][35][36][37][38][39][40][41][42][43][44], the self-localization of impurities in quasi-1D BEC media [45][46][47][48][49], polaronic spectral changes from a weak to strong coupling regime for attractive interactions [50][51][52][53][54], few-body physics around the unitarity limit [55][56][57][58][59], dynamics of the polaron formation [59][60][61][62], and open quantum dynamics [63][64][65]. Beside these 'conventional' atomic polarons, more e...…”

Section: Introductionmentioning

confidence: 99%

Bose polaron in spherical trap potentials: Spatial structure and quantum depletion

Takahashi¹,

Imai

Nakano

et al. 2019

Phys. Rev. A

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We investigate how the presence of a localized impurity in a Bose-Einstein condensate of trapped cold atoms that interact with each other weakly and repulsively affects the profile of the condensed and excited components at zero temperature. By solving the Gross-Pitaevskii and Bogoliubovde Gennes equations, we find that an impurity-boson contact attraction (repulsion) causes both components to change in spatial structure in such a way as to be enhanced (suppressed) around the impurity, while slightly declining (growing) in a far region from the impurity. Such behavior of the quantum depletion of the condensate can be understood by decomposing the impurity-induced change in the profile of the excited component with respect to the radial and azimuthal quantum number. A significant role of the centrifugal potential and the "hole" excitation level is thus clarified.

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Section: Introductionmentioning

confidence: 99%

Bose polaron in spherical trap potentials: Spatial structure and quantum depletion

Takahashi¹,

Imai

Nakano

et al. 2019

Phys. Rev. A

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“…In ultracold quantum gases, evidence of polarons has been found in systems with trapped ions [36] or systems with a single ion immersed in a degenerate quantum gas [37][38][39][40][41][42][43]. On the other hand, the atomic polaron has also been studied both experimentally and theoretically in systems of imbalanced Bose-Fermi mixtures [44][45][46][47][48][49] and Fermi-Fermi mixtures [50][51][52][53][54][55][56][57]. In the particular case of a system with impurities immersed in a bosonic bath, these impurities couple to bosonic excitations.…”

Section: Introductionmentioning

confidence: 99%

Polaronic effects in one- and two-band quantum systems

2015

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In this work we study the formation and dynamics of polarons in a system with a few impurities in a lattice immersed in a Bose-Einstein condensate (BEC). This system has been experimentally realized using ultracold atoms and optical lattices. Here we consider a two-band model for the impurity atoms, along with a Bogoliubov approximation for the BEC, with phonons coupled to impurities via both intra- and inter-band transitions. We decouple this Fr\"ohlich-like term by an extended two-band Lang-Firsov polaron transformation using a variational method. The new effective Hamiltonian with two (polaron) bands differs from the original Hamiltonian by modified coherent transport, polaron energy shifts and induced long-range interaction. A Lindblad master equation approach is used to take into account residual incoherent coupling between polaron and bath. This polaronic treatment yields a renormalized inter-band relaxation rate compared to Fermi's Golden Rule. For a strongly coupled two-band Fr\"ohlich Hamiltonian, the polaron is tightly dressed in each band and can not tunnel between them, leading to an inter-band self-trapping effect.Comment: 23 pages, 7 figure

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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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Excitonic states of an impurity in a Fermi gas

Cited by 4 publications

References 33 publications

Bose polaron in spherical trap potentials: Spatial structure and quantum depletion

Bose polaron in spherical trap potentials: Spatial structure and quantum depletion

Polaronic effects in one- and two-band quantum systems

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

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