Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms

Márton Kanász-Nagy, Yuto Ashida, Tao Shi, Cǎtǎlin Paşcu Moca, Tatsuhiko N. Ikeda, Simon Fölling, J. Ignacio Cirac, G. Zaránd, Eugene A. Demler

Research output: Contribution to journalArticle

12 Citations (Scopus)

Abstract

We propose a scheme to realize the Kondo model with tunable anisotropy using alkaline-earth atoms in an optical lattice. The new feature of our setup is Floquet engineering of interactions using time-dependent Zeeman shifts, that can be realized either using state-dependent optical Stark shifts or magnetic fields. The properties of the resulting Kondo model strongly depend on the anisotropy of the ferromagnetic interactions. In particular, easy-plane couplings give rise to Kondo singlet formation even though microscopic interactions are all ferromagnetic. We discuss both equilibrium and dynamical properties of the system that can be measured with ultracold atoms, including the impurity spin susceptibility, the impurity spin relaxation rate, as well as the equilibrium and dynamical spin correlations between the impurity and the ferromagnetic bath atoms. We analyze the nonequilibrium time evolution of the system using a variational non-Gaussian approach, which allows us to explore coherent dynamics over both short and long timescales, as set by the bandwidth and the Kondo singlet formation, respectively. In the quench-type experiments, when the Kondo interaction is suddenly switched on, we find that real-time dynamics shows crossovers reminiscent of poor man's renormalization group flow used to describe equilibrium systems. For bare easy-plane ferromagnetic couplings, this allows us to follow the formation of the Kondo screening cloud as the dynamics crosses over from ferromagnetic to antiferromagnetic behavior. On the other side of the phase diagram, our scheme makes it possible to measure quantum corrections to the well-known Korringa law describing the temperature dependence of the impurity spin relaxation rate. Theoretical results discussed in our paper can be measured using currently available experimental techniques.

Original languageEnglish
Article number155156
JournalPhysical Review B
Volume97
Issue number15
DOIs
Publication statusPublished - Apr 26 2018

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Earth (planet)
Impurities
impurities
Atoms
atoms
Anisotropy
interactions
Optical lattices
anisotropy
shift
Phase diagrams
baths
crossovers
Screening
screening
phase diagrams
engineering
Magnetic fields
bandwidth
magnetic permeability

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics

Cite this

Kanász-Nagy, M., Ashida, Y., Shi, T., Moca, C. P., Ikeda, T. N., Fölling, S., ... Demler, E. A. (2018). Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms. Physical Review B, 97(15), [155156]. https://doi.org/10.1103/PhysRevB.97.155156

Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms. / Kanász-Nagy, Márton; Ashida, Yuto; Shi, Tao; Moca, Cǎtǎlin Paşcu; Ikeda, Tatsuhiko N.; Fölling, Simon; Cirac, J. Ignacio; Zaránd, G.; Demler, Eugene A.

In: Physical Review B, Vol. 97, No. 15, 155156, 26.04.2018.

Research output: Contribution to journalArticle

Kanász-Nagy, M, Ashida, Y, Shi, T, Moca, CP, Ikeda, TN, Fölling, S, Cirac, JI, Zaránd, G & Demler, EA 2018, 'Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms', Physical Review B, vol. 97, no. 15, 155156. https://doi.org/10.1103/PhysRevB.97.155156
Kanász-Nagy M, Ashida Y, Shi T, Moca CP, Ikeda TN, Fölling S et al. Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms. Physical Review B. 2018 Apr 26;97(15). 155156. https://doi.org/10.1103/PhysRevB.97.155156
Kanász-Nagy, Márton ; Ashida, Yuto ; Shi, Tao ; Moca, Cǎtǎlin Paşcu ; Ikeda, Tatsuhiko N. ; Fölling, Simon ; Cirac, J. Ignacio ; Zaránd, G. ; Demler, Eugene A. / Exploring the anisotropic Kondo model in and out of equilibrium with alkaline-earth atoms. In: Physical Review B. 2018 ; Vol. 97, No. 15.
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