Ultrafast transient interference in pump-probe spectroscopy of band and Mott insulators

Abstract

Ultrafast pump-probe spectroscopy with high temporal and spectral resolutions provides new insight into ultrafast nonequilibrium phenomena. We propose that transient interference between pump and probe pulses is realized in pump-probe spectroscopy of band and Mott insulators, which can be observed only after recent developments of ultrafast spectroscopic techniques. A continuum structure in the excitation spectrum of band insulators is found to act as a medium for storing the spectral information of the pump pulse, and the spectrum detected by the probe pulse is interfered with by the medium, generating the transient interference in the energy domain. We also demonstrate the transient interference in the presence of electron correlations in a one-dimensional half-filled Hubbard model. Furthermore, bosons coupled to electrons additively contribute to the interference. Our finding will provide an interpretation of probe-energy-dependent oscillations recently observed in the pump-probe spectrum for a two-dimensional Mott insulator.

Ultrafast coupled charge and spin dynamics in strongly correlated NiO

“…However, our work provides the first observation of coherent long-lived many-body dynamics resulting from a coupling to the AFM background in a solid. Similar phenomena have been detected in cuprates exhibiting oscillations with a very short lifetime 52 , but their origin remains controversial 53 , 54 .…”

“…However, our work provides the first observation of coherent long-lived many-body dynamics resulting from a coupling to the AFM background in a solid. Similar phenomena have been detected in cuprates exhibiting oscillations with a very short lifetime 52 , but their origin remains controversial 53,54 . The experimental observations raise the central question how a strongly correlated solid can support coherent oscillations on such a long-time scale (up to 2 ps).…”

One-particle spectral functions of the one-dimensional Fermionic Hubbard model with one fermion per site at zero and finite magnetic fields

“…For instance, the coupling of the spin degrees of freedom to the Floquet sector with shifted transfer energies 2∆ M H ± ω by virtual absorption and emission of photons 2 of energy ω plays a key role in the dynamics of 1D Mott-Hubbard insulators at sub-picosecond timescales. This is an issue of both fundamental and technological interest 2,3 . The same applies to the more general problem of the 1D Mott-Hubbard insulators's interplay of charge and spin degrees of freedom.…”

“…The η-spins of projection −1/2 and +1/2 whose oneparticle state configurations are shown in this paper to be different for non-doped and doped Mott-Hubbard insulators, control important physical effects associated with other types of excitations. Specifically, they control third-harmonic generation spectroscopy, which plays a key role in the realization of all-optical switching, modulating, and computing devices of modern optical technology 3,37 . Indeed, excited states containing a pair of η-spins with opposite projection −1/2 and +1/2 are behind the anomalously enhanced third-order nonlinear optical susceptibility χ (3) , as observed in the 1D Mott-Hubbard insulator Sr 2 CuO 3 37 .…”

“…Specifically, they control third-harmonic generation spectroscopy, which plays a key role in the realization of all-optical switching, modulating, and computing devices of modern optical technology 3,37 . Indeed, excited states containing a pair of η-spins with opposite projection −1/2 and +1/2 are behind the anomalously enhanced third-order nonlinear optical susceptibility χ (3) , as observed in the 1D Mott-Hubbard insulator Sr 2 CuO 3 37 . Within a description in terms of the 1D half-filled Hubbard model, this follows from odd-and even-parity states being nearly degenerate with a large transition dipole moment between them.…”