Photo-induced eta-pairing in the Hubbard model

 "Eta-pair" is a special type of the Cooper pair whose phase alternates from site to site. The idea of the eta-pairing was first proposed by mathematical physicist Chen-Ning Yang in more than 30 years ago as the energy eigenstates of the Hubbard model. However, since it was a purely mathematical concept, it has been understood as the virtual phenomenon which would not take place in the real world.
The research group of Tomonori Shirakawa, Sandro Sorella from SISSA, and Tatsuya Kaneko, Seiji Yunoki from RIKEN found a new pathway for realizing the eta-pairing states. By applying the unbiased time-dependent numerical methods to the Mott insulating states in the Hubbard model, the research group found that the pulse irradiation significantly enhances the pairing correlation for the eta-pairing as a consequence of the non-linear processes of the photo-excitation.

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Dated: March 12, 2019