We report on the experimental observation of multiorbital polarons in a two-dimensional Fermi gas of ^{173}Yb atoms formed by mobile impurities in the metastable ^{3}P_{0} orbital and a Fermi sea in the ground-state ^{1}S_{0} orbital. We spectroscopically probe the energies of attractive and repulsive polarons close to an orbital Feshbach resonance and characterize their coherence by measuring the quasiparticle residue. For all probed interaction parameters, the repulsive polaron is a long-lived quasiparticle with a decay rate more than 2 orders of magnitude below its energy. We formulate a many-body theory, which accurately treats the interorbital interactions in two dimensions and agrees well with the experimental results. Our work paves the way for the investigation of many-body physics in multiorbital ultracold Fermi gases.We report on the experimental observation of multiorbital polarons in a two-dimensional Fermi gas of ^{173}Yb atoms formed by mobile impurities in the metastable ^{3}P_{0} orbital and a Fermi sea in the ground-state ^{1}S_{0} orbital. We spectroscopically probe the energies of attractive and repulsive polarons close to an orbital Feshbach resonance and characterize their coherence by measuring the quasiparticle residue. For all probed interaction parameters, the repulsive polaron is a long-lived quasiparticle with a decay rate more than 2 orders of magnitude below its energy. We formulate a many-body theory, which accurately treats the interorbital interactions in two dimensions and agrees well with the experimental results. Our work paves the way for the investigation of many-body physics in multiorbital ultracold Fermi gases.

arXiv:1901.09105Physical Review LettersMay 17, 201975 citations

Finite-range effects in the two-dimensional repulsive Fermi polaron

Raúl Bombín, Viktor Cikojević, Juan Sánchez-Baena +1 more

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 $^{173}\mathrm{Yb}$ atoms [N. Darkwah Oppong et al., Phys. Rev. Lett. 122, 193604 (2019)]. We use the diffusion Monte Carlo method to report properties such as the polaron energy and the quasiparticle residue that have been measured in that experiment. To provide insight into the quasiparticle character of the problem, we also report results for the effective mass. We show that the effective range, together with the scattering length, is needed in order to reproduce the experimental results. Using different model potentials for the interaction between the Fermi sea and the impurity, we show that it is possible to establish a regime of universality, in terms of these two parameters, that includes the whole experimental regime. This illustrates the relevance of quantum fluctuations and beyond mean-field effects to correctly describe the Fermi polaron problem.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 $^{173}\mathrm{Yb}$ atoms [N. Darkwah Oppong et al., Phys. Rev. Lett. 122, 193604 (2019)]. We use the diffusion Monte Carlo method to report properties such as the polaron energy and the quasiparticle residue that have been measured in that experiment. To provide insight into the quasiparticle character of the problem, we also report results for the effective mass. We show that the effective range, together with the scattering length, is needed in order to reproduce the experimental results. Using different model potentials for the interaction between the Fermi sea and the impurity, we show that it is possible to establish a regime of universality, in terms of these two parameters, that includes the whole experimental regime. This illustrates the relevance of quantum fluctuations and beyond mean-field effects to correctly describe the Fermi polaron problem.

arXiv:2008.10510Physical Review AApr 8, 20216 citations

Downfolding a quantum many-body system: Quasi-one-dimensional Fermi polaron

L. Barisic, Giuliano Orso, Kris Van Houcke +1 more

Physical Review AOct 21, 20260 citations

Fermi-polaron-like effects in a one-dimensional (1D) optical lattice

M. J. Leskinen, O H T Nummi, Francesco Massel +1 more

We study a highly imbalanced Fermi gas in a one-dimensional (1D) optical lattice from the polaronic point of view. The time-evolving block decimation algorithm is used to calculate the ground state and dynamics of the system. We find polaronic behaviour qualitatively similar to that in the recent experiment by Schirotzek et al (2009 Phys. Rev. Lett. 102 230402), where radio-frequency (rf) spectroscopy was used to observe polarons in 3D space. In the weakly interacting limit, our exact results are in excellent agreement with a polaron ansatz, and in the strongly interacting limit, the results match with an approximative solution of the Bethe ansatz (BA), suggesting crossover from a quasiparticle to a charge-density excitation regime.We study a highly imbalanced Fermi gas in a one-dimensional (1D) optical lattice from the polaronic point of view. The time-evolving block decimation algorithm is used to calculate the ground state and dynamics of the system. We find polaronic behaviour qualitatively similar to that in the recent experiment by Schirotzek et al (2009 Phys. Rev. Lett. 102 230402), where radio-frequency (rf) spectroscopy was used to observe polarons in 3D space. In the weakly interacting limit, our exact results are in excellent agreement with a polaron ansatz, and in the strongly interacting limit, the results match with an approximative solution of the Bethe ansatz (BA), suggesting crossover from a quasiparticle to a charge-density excitation regime.

arXiv:1003.6037New Journal of PhysicsJul 30, 201014 citations

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}\mathrm{Yb}

atoms [N. Darkwah Oppong et al., Phys. Rev. Lett. 122, 193604 (2019)]. We use the diffusion Monte Carlo method to report properties such as the polaron energy and the quasiparticle residue that have been measured in that experiment. To provide insight into the quasiparticle character of the problem, we also report results for the effective mass. We show that the effective range, together with the scattering length, is needed in order to reproduce the experimental results. Using different model potentials for the interaction between the Fermi sea and the impurity, we show that it is possible to establish a regime of universality, in terms of these two parameters, that includes the whole experimental regime. This illustrates the relevance of quantum fluctuations and beyond mean-field effects to correctly describe the Fermi polaron problem.