Localized Magnetic Moments with Tunable Spin Exchange in a Gas of Ultracold Fermions

Riegger, Luis; Oppong, Nelson Darkwah; Höfer, M.; Fernandes, Diogo Rio; Bloch, Immanuel; Fölling, Simon

doi:10.1103/physrevlett.120.143601

Cited by 135 publications

(149 citation statements)

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“…In particular, they are central to the study of quantum gases or the generation of entanglement. Recently, large spin-exchange interactions have been measured with fermionic 173 Yb [11,12], which is promising for the simulation of quantum impurity models [13]. While atomic interactions are usually detrimental in frequency metrology [1], degenerate quantum gases may help to improve the accuracy of optical clocks by offering a better control over interaction effects [1], as suggested by a recent demonstration with a degenerate Fermi gas of 87 Sr [14].…”

Section: Introductionmentioning

confidence: 99%

Clock spectroscopy of interacting bosons in deep optical lattices

et al. 2017

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We report on high-resolution optical spectroscopy of interacting bosonic 174 Yb atoms in deep optical lattices with negligible tunneling. We prepare Mott insulator phases with singly-and doubly-occupied isolated sites and probe the atoms using an ultra-narrow 'clock' transition. Atoms in singly-occupied sites undergo long-lived Rabi oscillations. Atoms in doubly-occupied sites are strongly affected by interatomic interactions, and we measure their inelastic decay rates and energy shifts. We deduce from these measurements all relevant collisional parameters involving both clock states, in particular the intra-and inter-state scattering lengths.

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Section: Introductionmentioning

confidence: 99%

Clock spectroscopy of interacting bosons in deep optical lattices

et al. 2017

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“…In the latter, further progress hinges on an accurate non-perturbative solution for the nonequilibrium Green functions of an effective quantum impurity model. Such a solution, beyond allowing timeresolved spectroscopies of correlated lattice systems within DMFT to be addressed [43][44][45][46][47], would also be useful in understanding time-resolved scanning tunnelling microscopy of nanoscale systems [48] and proposed cold atom realizations of Kondo correlated states [49][50][51][52], which could be probed with real-time radio-frequency spectroscopy [53][54][55].In this Letter, we use the time-dependent numerical renormalization group (TDNRG) approach [56][57][58][59][60][61][62] to calculate the retarded two-time Green function, G(t 1 = t + t , t 2 = t), and associated spectral function, A(ω, t), of the Anderson impurity model in response to a quench at time t = 0, and apply this to investigate in detail the time evolution of the Kondo resonance. This topic has been addressed before within several approaches, including the non-crossing approximation [26,63], conserving approximations [64] and within CTQMC for quantum dots out of equilibrium [32].…”

mentioning

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confidence: 99%

Time Evolution of the Kondo Resonance in Response to a Quench

Nghiem

Costi

2017

Phys. Rev. Lett.

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We investigate the time evolution of the Kondo resonance in response to a quench by applying the timedependent numerical renormalization group (TDNRG) approach to the Anderson impurity model in the strong correlation limit. For this purpose, we derive within TDNRG a numerically tractable expression for the retarded two-time nonequilibrium Green function G(t + t , t), and its associated time-dependent spectral function, A(ω, t), for times t both before and after the quench. Quenches from both mixed valence and Kondo correlated initial states to Kondo correlated final states are considered. For both cases, we find that the Kondo resonance in the zero temperature spectral function, a preformed version of which is evident at very short times t → 0 + , only fully develops at very long times t 1/T K , where T K is the Kondo temperature of the final state. In contrast, the final state satellite peaks develop on a fast time scale 1/Γ during the time interval −1/Γ t +1/Γ, where Γ is the hybridization strength. Initial and final state spectral functions are recovered in the limits t → −∞ and t → +∞, respectively. Our formulation of two-time nonequilibrium Green functions within TDNRG provides a first step towards using this method as an impurity solver within nonequilibrium dynamical mean field theory.Introduction.-The nonequilibrium properties of strongly correlated quantum impurity models continue to pose a major theoretical challenge. This contrasts with their equilibrium properties, which are largely well understood [1], or can be investigated within a number of highly accurate methods, such as the numerical renormalization group method (NRG) [2][3][4][5], the continuous time quantum Monte Carlo (CTQMC) approach [6], the density matrix renormalization group [7], or the Bethe ansatz method [8,9]. Quantum impurity models far from equilibrium are of direct relevance to several fields of research, including charge transfer effects in lowenergy ion-surface scattering [10][11][12][13][14][15][16][17], transient and steady state effects in molecular and semiconductor quantum dots [18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36], and also in the context of dynamical mean field theory (DMFT) of strongly correlated lattice models [37][38][39], as generalized to nonequilibrium [40][41][42]. In the latter, further progress hinges on an accurate non-perturbative solution for the nonequilibrium Green functions of an effective quantum impurity model. Such a solution, beyond allowing timeresolved spectroscopies of correlated lattice systems within DMFT to be addressed [43][44][45][46][47], would also be useful in understanding time-resolved scanning tunnelling microscopy of nanoscale systems [48] and proposed cold atom realizations of Kondo correlated states [49][50][51][52], which could be probed with real-time radio-frequency spectroscopy [53][54][55].In this Letter, we use the time-dependent numerical renormalization group (TDNRG) approach [56][57][58][59][60][61][62] to calculate the retarded two-time ...

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“…Applications of this technique can reach beyond the density probing demonstrated here and might allow, for example, thermometry of the BEC. Furthermore, the coupling of individual particles to a spin bath constitutes a realization of the spin‐boson model, complementary to a recent realization in a fermionic system …”

Section: Spin Dynamic Of Impurities In a Gasmentioning

confidence: 99%

Motional and Spin Dynamics of Individual Neutral Impurities in an Ultracold Gas

Schmidt¹,

Mayer²,

Lausch³

et al. 2019

Physica Status Solidi (b)

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Recent studies on the dynamics of single, neutral impurities immersed in an ultracold gas are reviewed. This paradigmatic model system is realized by the controlled doping of single Caesium atoms into an ultracold Rubidium gas. Interaction between the impurity and the gas in both the motional and internal degrees of freedom is studied for a broad range of bath temperatures in the thermal and quantum‐degenerate regime. Tracing single‐atom diffusion it is found that, even for a granular bath, where the assumption of a continuous medium is not fulfilled, a modified Langevin equation yields excellent predictions for tracer diffusion. Numerical modeling of impurity dynamics in a three‐dimensional superfluid bath shows the emergence of a prethermalized state for intermediate times due to the existence of a superfluid critical momentum, while for lower dimensions the effect of thermal phonons dominates and obstructs the formation of such nonthermal states. Finally, unleashing the quasi‐spin degree of freedom, the authors observe and control spin‐exchange dynamics between individual impurities and the bath. Moreover, a regime of sympathetic impurity cooling is realized, where the internal‐state coherence of the impurity is preserved. In the future, control over the motional and spin‐degree of freedom will enable using individual impurities as thermalized, localized, minimally invasive quantum probes for a quantum fluid.

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Localized Magnetic Moments with Tunable Spin Exchange in a Gas of Ultracold Fermions

Cited by 135 publications

References 40 publications

Clock spectroscopy of interacting bosons in deep optical lattices

Clock spectroscopy of interacting bosons in deep optical lattices

Time Evolution of the Kondo Resonance in Response to a Quench

Motional and Spin Dynamics of Individual Neutral Impurities in an Ultracold Gas

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