Photoinduced η -pairing at finite temperatures

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

doi:10.1103/physrevresearch.2.032008

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.

Highlights

Optical pumping is an excellent tool to investigate complex few- and many-body systems and makes it possible to create new phases of quantum matter with tunable properties [1,2,3,4]
For lowamplitude pulses, the peak structure of the pair-correlation function is essentially the same as that obtained for the optical spectrum in the ground state, implying that the photoinduced state might result from an η-pairing mechanism
We have demonstrated light-pulse photoinduced η-pairing in the one-dimensional half-filled Hubbard model at both zero and finite temperatures by means of a de facto approximation-free numerical approach

Summary

Rapid Communications

Satoshi Ejima ,1,2 Tatsuya Kaneko, Florian Lange, Seiji Yunoki, and Holger Fehske 1 1Institute of Physics, University Greifswald, 17489 Greifswald, Germany. 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 η-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 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

Introduction

Published by the American Physical Society

Conclusions