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arXiv · 2508.00296

High-harmonic generation during ultrafast melting of a Mott insulating state

Ryohei Ikeda·Yuta Murakami·Daiki Sakai·Tatsuya Miyamoto·Toshimitsu Ito·Hiroshi Okamoto
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Abstract

Solids in an intense laser field show high-harmonic generation (HHG), which can provide information on carrier dynamics and band structures in weakly correlated systems. In strongly correlated systems, a laser field can induce a transition between the various electronic phases formed by the entanglement of charge, spin, and orbital degrees of freedom via carrier generation. The HHG accompanying this process can reflect information on the nonequilibrium electronic-state dynamics along the oscillating field-an aspect that remains unresolved to date. Here, we show that an intense mid-infrared (MIR) pulse induces melting of a Mott-insulator state in a one-dimensional cuprate, Sr2CuO3, the evolution of which leaves a trace in the HH spectra. When the electric-field amplitude exceeds 6 MV/cm, carriers are efficiently generated and each harmonic frequency decreases from odd multiples of the MIR frequency. Dynamical mean-field theory (DMFT) presents a possibility that these redshifts originate from a series of electronic-structure reconstructions in each electric-field cycle during the melting of the Mott-insulator state, which modifies the radiation phase from carrier recombination cycle-by-cycle. This phenomenon is negligible in rigid-band systems. This experimental-theoretical study suggests that HH spectroscopy has the potential to obtain information on the cycle-by-cycle dynamics of nonequilibrium transitions in correlated materials.

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Ryohei Ikeda, Yuta Murakami, Daiki Sakai, Tatsuya Miyamoto, Toshimitsu Ito, Hiroshi Okamoto. 2025-08-01. High-harmonic generation during ultrafast melting of a Mott insulating state. https://arxiv.org/abs/2508.00296

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