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We have observed Fermi polarons, dressed spin down impurities in a spin up Fermi sea of ultracold atoms. The polaron manifests itself as a narrow peak in the impurities' rf spectrum that emerges from a broad incoherent background. We…

Other Condensed Matter · Physics 2009-06-09 Andre Schirotzek , Cheng-Hsun Wu , Ariel Sommer , Martin W. Zwierlein

We have conducted a thorough theoretical and numerical investigation of the electronic susceptibility, polarizability, plasmons, their damping rates, as well as the static screening in pseudospin-1 Dirac cone materials with a flat band, or…

We investigate the properties of a strongly interacting imbalanced mixture of bosonic $^{41}$K impurities immersed in a Fermi sea of ultracold $^6$Li atoms. This enables us to explore the Fermi polaron scenario for large impurity…

In this review, we discuss the properties of a few impurity atoms immersed in a gas of ultracold fermions, the so-called Fermi polaron problem. On one side, this many-body system is appealing because it can be described almost exactly with…

Quantum Gases · Physics 2014-02-26 Pietro Massignan , Matteo Zaccanti , Georg M. Bruun

We consider the Fermi polaron problem of an impurity hopping around a two-dimensional square lattice and interacting with a sea of fermions at given filling factor. When the interaction is attractive, we find standard Fermi polaron…

Quantum Gases · Physics 2024-08-21 Hui Hu , Jia Wang , Xia-Ji Liu

We revisit the polaron-molecule transition in three-dimensional(3D) fermion systems using the well-established variational approach. The molecule is found to be intrinsically unstable against lowest-order particle-hole excitations, and it…

Quantum Gases · Physics 2021-01-04 Xiaoling Cui

We study an impurity atom in a two-dimensional Fermi gas using variational wave functions for (i) an impurity dressed by particle-hole excitations (polaron) and (ii) a dimer consisting of the impurity and a majority atom. In contrast to…

Quantum Gases · Physics 2011-02-22 Sascha Zöllner , G. M. Bruun , C. J. Pethick

Mobile impurities in cold atomic gases constitute a new platform for investigating polaron physics. Here we show that when impurity atoms interact with a two-dimensional Fermi gas with quadratic band touching the polaron picture may either…

Quantum Gases · Physics 2016-12-14 M. A. Caracanhas , R. G. Pereira

We investigate thermal evolution of radio-frequency (RF) spectra of a spin-imbalanced Fermi gas near a Feshbach resonance in which degenerate Fermi-polaron and classical Boltzmann-gas regimes emerge in the low-temperature and…

Quantum Gases · Physics 2019-06-19 Hiroyuki Tajima , Shun Uchino

An impurity atom immersed in an ultracold atomic Fermi gas can form a quasiparticle, so-called Fermi polaron, due to impurity-fermion interaction. We consider a three-dimensional homogeneous dipolar Fermi gas as a medium, where the…

By using both diagrammatic theory and Chevy ansatz approach, we derive an exact set of equations, which determines the spectral function of Fermi polarons with multiple particle-hole excitations at nonzero temperature. In the diagrammatic…

Quantum Gases · Physics 2024-03-15 Hui Hu , Jia Wang , Xia-Ji Liu

We consider an impurity problem in a quasi-two-dimensional Fermi gas, where a spin-down impurity is immersed in a Fermi sea of N spin-up atoms. Using a variational approach and an effective two-channel model, we obtain the energies of the…

Atomic Physics · Physics 2022-08-17 Yue-Ran Shi , Jin-Ge Chen , Kuiyi Gao , Wei Zhang

The two-dimensional model of itinerant electrons coupled to an anti-ferromagnetic order parameter is considered. In the mean field solution the Fermi surface undergoes reconstruction, and breaks into disconnected ``pockets''. We have…

Strongly Correlated Electrons · Physics 2010-04-09 M. Khodas , A. M. Tsvelik

We apply the diagrammatic Monte Carlo approach to three-dimensional Fermi-polaron systems with mass-imbalance, where an impurity interacts resonantly with a noninteracting Fermi sea whose atoms have a different mass. This method allows to…

Quantum Gases · Physics 2015-04-23 Peter Kroiss , Lode Pollet

Atom-ion hybrid systems are promising platforms for the quantum simulation of polaron physics in certain quantum materials. Here, we investigate the ionic Fermi polaron, a charged impurity in a polarized Fermi bath, at zero temperature…

Quantum Gases · Physics 2024-12-04 Renato Pessoa , S. A Vitiello , L. A Peña Ardila

We study the motion of a slow quantum impurity in one-dimensional environments focusing on systems of strongly interacting bosons and weakly interacting fermions. While at zero temperature the impurity motion is frictionless, at low…

Quantum Gases · Physics 2020-03-11 Aleksandra Petkovic

We study the repulsive Fermi polaron in a two-component, two-dimensional system of fermionic atoms inspired by the results of a recent experiment with $^{173}$Yb atoms [N. Darkwah Oppong \textit{et al.}, Phys. Rev. Lett. \textbf{122},…

Quantum Gases · Physics 2021-04-14 Raúl Bombín , Viktor Cikojević , Juan Sánchez-Baena , Jordi Boronat

We investigate the system of a heavy impurity immersed in a degenerated Fermi gas, where the impurity's internal degree of freedom (pseudospin) is manipulated by a series of radiofrequency (RF) pulses at several different times. Applying…

Quantum Gases · Physics 2023-01-18 Jia Wang

We consider a mobile impurity coupled to an ideal Fermi gas in one spatial dimension through an attractive contact interaction. We calculate the quasi-particle residue $Z$ exactly, based on Bethe Ansatz and diagrammatic Monte Carlo methods,…

We present a new method to detect Fermi surface instabilities for interacting systems at finite temperature. We first apply it to a list of cases studied previously, recovering already known results in a very economic way, and obtaining…

Strongly Correlated Electrons · Physics 2015-06-05 P. Rodríguez Ponte , D. C. Cabra , N. Grandi