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Exploring kinetically induced bound states in triangular lattices with ultracold atoms: spectroscopic approach

by Ivan Morera Navarro, Christof Weitenberg, Klaus Sengstock, Eugene Demler

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Submission summary

Authors (as registered SciPost users): Ivan Morera Navarro
Submission information
Preprint Link: scipost_202402_00025v1  (pdf)
Date accepted: 2024-02-28
Date submitted: 2024-02-16 11:04
Submitted by: Morera Navarro, Ivan
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Atomic, Molecular and Optical Physics - Theory
  • Condensed Matter Physics - Theory
Approaches: Theoretical, Computational


Quantum simulations with ultracold fermions in triangular optical lattices have recently emerged as a new platform for studying magnetism in frustrated systems. Experimental realizations of the Fermi Hubbard model revealed striking contrast between magnetism in bipartite and triangular lattices. In bipartite lattices magnetism is strongest at half filling, and doped charge carriers tend to suppress magnetic correlations. In triangular-type lattices for large $U/t$ and $t>0$, antiferromagnetism (ferromagnetism) gets enhanced by doping away from $n=1$ with holes (doublons) because kinetic energy of dopants can be lowered through developing magnetic correlations, corresponding to formation of magnetic polarons~\cite{Batista2017}. Snapshots of many-body states obtained with quantum gas microscopes~\cite{Greiner2022,Lebrat2023,Prichard2023} demonstrated existence of magnetic polarons by revealing the magnetic correlations around dopants at temperatures that considerably exceed superexchange energy scale. In this paper we discuss theoretically that additional insight into properties of magnetic polarons in triangular lattices can be achieved using spectroscopic experiments with ultracold atoms. We consider starting from a spin polarized state with small hole doping and applying a two-photon Raman photoexcitation, which transfers atoms into a different spin state. We show that such magnon injection spectra exhibit a separate peak corresponding to formation of a bound state between a hole and a magnon. This polaron peak is separated from the simple magnon spectrum by energy proportional to single particle tunneling and can be easily resolved with currently available experimental techniques. For some momentum transfer there is an additional peak corresponding to photoexciting a bound state between two holes and a magnon. We point out that in two component Bose mixtures in triangular lattices one can also create dynamical magnetic polarons, with one hole and one magnon forming a repulsive bound state.

Author comments upon resubmission

We thank you for your assessment on our manuscript and considering it for publication in Sci Post Physics. We are pleased to see that both Referee’s have recommended publication in Sci Post and we thank them for their valuable reports and their constructive criticism. Addressing the Referee’s comments has helped us to further improve our manuscript. With the changes made to the manuscript, we hope that we are able to exhaustively address the referees’ comments. With these changes in place, we resubmit our work, and we ask for your kind reconsideration of our manuscript. We thank you very much for your time, effort, and consideration.
Below we provide a detailed list of changes to the manuscript and a response to the all criticisms
raised by the referees. Moreover, our response to the Referee’s also exhaustively covers their comments.

List of changes

We provide a list of the most important changes introduced in the manuscript. However, our response to the referees contains a detailed description of all changes made to the manuscript.

1. We have included a new section (Sec. 5.3) providing details on the calculation of the photoexcitation spectrum for the two-body problem and how to get the finite temperature photoexcitation spectrum.

2. We have improved the phrasing of the abstract and included a reference to the original theoretical work discussing antiferromagnetic polarons in the triangular lattice.

3. We have corrected typos in the manuscript and clarified notation in different equations.

4. We have included a discussion on kinetic frustration in Sec. 3.

5. We have incorporated new references on magnetic polarons in square lattices and Lanczos algorithm.

6. We have provided a discussion on the experimental feasibility of resolving the trimer peak.

Published as SciPost Phys. 16, 081 (2024)

Reports on this Submission

Anonymous Report 1 on 2024-2-22 (Invited Report)


The authors have given a detailed response to my previous report and implemented suitable changes to the manuscript.

I now fully support publication of the manuscript in SciPost Physics with no further comments.

  • validity: high
  • significance: good
  • originality: good
  • clarity: high
  • formatting: excellent
  • grammar: excellent

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