Photoinduced $\eta$-pairing at finite temperatures

TL;DR

This study demonstrates that laser pulses can induce $ ext{eta}$-pairing correlations in a half-filled fermionic Hubbard chain at zero and low temperatures, with effects diminishing at higher temperatures but showing persistent features under certain conditions.

Contribution

It provides the first numerical evidence of photoinduced $ ext{eta}$-pairing at finite temperatures using advanced tensor network techniques, highlighting the role of laser parameters and temperature effects.

Findings

Optimal laser parameters induce $ ext{eta}$-pairing correlations.

Correlations diminish at higher temperatures and long times.

Persistent pair correlations occur at high frequencies and strong Coulomb coupling.

Abstract

We numerically prove photoinduced $\eta$-pairing in a half-filled fermionic Hubbard chain at both zero and finite temperature. The result, obtained by combining the matrix-product-state based infinite time-evolving block decimation technique and the purification method, applies to the thermodynamic limit. Exciting the Mott insulator by a laser electric field docked on via the Peierls phase, we track the time-evolution of the correlated many-body system and determine the optimal parameter set for which the nonlocal part of the $\eta$-pair correlation function becomes dominant during the laser pump at zero and low temperatures. These correlations vanish at higher temperatures and long times after pulse irradiation. In the high laser frequency strong Coulomb coupling regime we observe a remnant enhancement of the Brillouin-zone boundary pair-correlation function also at high temperatures, if the Hubbard interaction is about a multiple of the laser frequency, which can be attributed to an enhanced double occupancy in the virtual Floquet state.