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arXiv:2003.10818 · International Conference on Strongly Correlated Electron Systems (SCES)

Photoinduced η-pairing in One-dimensional Mott Insulators

Satoshi Ejima, Tatsuya Kaneko, Florian Lange, Seiji Yunoki, Holger Fehske

Published Mar 18, 2020• 8 citations
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Abstract

Employing the density-matrix renormalization group technique in the matrix-product-state representation, we investigate the photoexcited superconducting correlations induced by the η-pairing mechanism in the half-filled Hubbard chain.We estimate the characteristic pair correlation function and verify the accuracy of our numerical results by comparison with exact-diagonalization data for small systems.The optimal parameter set of the pump that most enhances the η-pair correlations, is calculated in the strong-coupling regime.For such a pump, we explore the possibility of quasi-long-range order.

DOI
10.7566/jpscp.30.011184

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Employing the density-matrix renormalization group technique in the matrix-product-state representation, we investigate the photoexcited superconducting correlations induced by the η-pairing mechanism in the half-filled Hubbard chain.We estimate the characteristic pair correlation function and verify the accuracy of our numerical results by comparison with exact-diagonalization data for small systems.The optimal parameter set of the pump that most enhances the η-pair correlations, is calculated in the strong-coupling regime.For such a pump, we explore the possibility of quasi-long-range order.
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Utilizing time-evolution techniques in (infinite) matrix-product-state representation, we study the non-equilibrium dynamics of driven Mott insulators and demonstrate photoinduced \eta η pairing directly in the thermodynamic limit. Analyzing the time evolution of the corresponding pairing correlations, we determine the optimal laser pump parameters for which long-range \eta η -pairing becomes dominant after pulse irradiation. The time-dependent photoemission spectra for this optimal pump parameter set show clear signatures of the photoinduced insulator-to-metal phase transition related to the formation of \eta η pairs.
Entanglement analysis of photoinduced η\etaη-pairing states
Abstract Simulating the von Neumann and second-order Rényi entropies of driven Mott insulators, we examine the entanglement dynamics of the η\etaη η -pairing state in the one-dimensional half-filled Hubbard model after pulse irradiation. Corresponding data are obtained by means of the infinite time-evolving block decimation technique directly in the thermodynamic limit. For optimal pump-pulse parameters the temporal course of the entanglement entropies shows the characteristic entanglement growth due to the increase of η\etaη η -pairing correlations.
We study photoinduced optical responses of one-dimensional strongly correlated electron systems. The optical conductivity spectra are calculated for the ground state and a photoexcited state in the one-dimensional Hubbard model at half filling by using the exact diagonalization method. It is found that, in the Mott insulator phase, the photoexcited state has large spectral weights including the Drude weight below the optical gap. As a consequence, the spectral weight above the optical gap is largely reduced. These results imply that a metallic state is induced by photoexcitation. Comparison between the photoexcited and hole-doped states shows that the photoexcitation is similar to chemical doping.
We use time-evolution techniques for (infinite) matrix product states to calculate, directly in the thermodynamic limit, the time-dependent photoemission spectra and dynamic structure factors of the half-filled Hubbard chain after pulse irradiation.These quantities exhibit clear signatures of the photoinduced phase transition from insulator to metal that occurs because of the formation of so-called η pairs.In addition, the spin dynamic structure factor loses spectral weight in the whole momentum space, reflecting the suppression of antiferromagnetic correlations due to the buildup of η-pairing states.The numerical method demonstrated in this work can be readily applied to other one-dimensional models driven out of equilibrium by optical pumping.