Polaron physics with ultracold atoms and beyond (Dr. R. Schmidt)

  • Date: Jan 25, 2018
  • Time: 11:00 - 12:00
  • Speaker: Dr. Richard Schmidt
  • MPQ, Theory Division
  • Room: New Lecture Hall, Room B 0.32
  • Host: MPQ, Theory Division
When an impurity is immersed into an environment, it changes its properties due to its interactions with the surrounding medium.

The impurity is dressed by many-body excitations and forms a quasiparticle, the polaron. Depending on the character of the environment and the form of interactions, different types of polarons are created. In this talk, I will review recent experimental and theoretical progress on studying the many-body physics of polarons in ultracold atomic systems [1], and discuss related polaronic phenomena encountered in two-dimensional semiconductors [2] and the study of rotating molecules in superfluid Helium [3]. In the second part of the talk I will then focus on impurities interacting with bosonic quantum gases. Specifically, I will discuss progress on the theoretical description of Rydberg excitations coupled to Bose-Einstein condensates. In such systems the interaction between the Rydberg atom and the Bose gas is mediated by the Rydberg electron. This gives rise to a new polaronic dressing mechanisms, where instead of collective excitations, molecules of gigantic size dress the Rydberg impurity. We develop a functional determinant approach [4] to describe the dynamics of such Rydberg systems which incorporates atomic and many-body theory. Using this approach we predict the appearance of a superpolaronic state which has recently been observed in experiments [5,6].


[1] R. Schmidt, M. Knap, D. A. Ivanov, J.-S. You, M. Cetina, and E. Demler, Rep. Prog. Phys. 81, 024401 (2018).
[2] M. Sidler et al., Nature Physics 13, 255 (2017)
[3] R. Schmidt, and M. Lemeshko, Phys. Rev. Lett. 114, 203001 (2015);
[4] R. Schmidt, H. Sadeghpour, and E. Demler, Phys. Rev. Lett. 116, 105302 (2016).
[5] F. Camargo et al., arXiv:1706.03717 (2017).
[6] R. Schmidt et al., arXiv:1709.01838 (2017).

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