2020/07/30 by Yasuhiro Tanaka, Kenji Yonemitsu
Chemistry · Materials Science · Physics and Astronomy · #Atomic physics #Chemistry #Cold Atom Physics and Bose-Einstein Condensates #Condensed matter physics #Dipole #Electron #Electronic and Structural Properties of Oxides #Excitation #Exciton #Hubbard model #Oscillation (cell signaling) #Phonon #Photoexcitation #Physics #Physics of Superconductivity and Magnetism #Quantum #Quantum electrodynamics #Quantum mechanics #Rabi cycle #Rabi frequency #Superconductivity #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.102.075118
published as Phys. Rev. B 102, 075118 (2020) · 21 pages, 37 figures, to be published in Phys. Rev. B
arxiv created 2020/07/30 · openalex created_date 2020/08/03 · openalex publication_date 2020/08/13 · arxiv updated 2020/08/18 · openalex updated_date 2026/08/06
We investigate the condition for the photoinduced enhancement of an excitonic order in a two-orbital Hubbard model, which has been theoretically proposed in our previous work [Phys. Rev. B 97, 115105 (2018)], and analyze it from the viewpoint of the Rabi oscillation. Within the mean-field approximation, we simulate real-time dynamics of an excitonic insulator with a direct gap, where the pair condensation in the initial state is of BEC nature and the photoexcitation is introduced by electric dipole transitions. We first discuss that in the atomic limit our model is reduced to a two-level system that undergoes the Rabi oscillation, so that for single cycle pulses physical quantities after the photoirradiation are essentially determined by the ratio of the Rabi frequency to the pump-light frequency. Then, it is shown that this picture holds even in the case of nonzero transfer integrals where each one-particle state exhibits the Rabi oscillation leading to the enhancement of the excitonic order. We demonstrate that effects of electron-phonon interactions do not alter the results qualitatively. We also examine many-body dynamics by the exact diagonalization method on small clusters, which strongly suggests that our mechanism for the enhancement of the excitonic order survives even when quantum fluctuations are taken into account.