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Real-time ab initio description of the photon-echo mechanisms in extended systems: the case study of bulk GaAs

by M. D'Alessandro, D. Sangalli

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Submission summary

Authors (as registered SciPost users): Marco D'Alessandro
Submission information
Preprint Link:  (pdf)
Date accepted: 2022-06-01
Date submitted: 2022-05-30 09:25
Submitted by: D'Alessandro, Marco
Submitted to: SciPost Physics
Ontological classification
Academic field: Physics
  • Condensed Matter Physics - Computational
Approaches: Theoretical, Computational


In this paper we present an ab initio real-time analysis of free polarization decay and photon echo in extended systems. As a prototype material, we study bulk GaAs driven by ultra-short laser pulses of 10 fs (energy spread of 0.4 eV), with frequency tuned in the continuum of the optical spectrum. We compute the electronic polarization P(t), and define a computational procedure to extract the echo signal in the dipole approximation. Results are obtained in both the low and high field regime, and compared with a two-levels system (TLS) model, with parameters extracted from the ab initio simulations. ab initio results are in optimal agreement with the TLS in the low-field case, whereas some differences are observed in the high-field regime where the multi-band nature of GaAs becomes relevant. In the high field regime we compute the pulse area, and look for fluences with pulse area close to {\pi}. We highlight that such fluences are well below the damage threshold of GaAs. However a unique value of the area cannot be defined, due to the strong dependence of the transition dipoles in the energy window excited by the laser pulse.

Author comments upon resubmission

Hereby, we submit a revised version of the paper.
The suggestions and criticisms of the referees have been addressed and some
(minor) modifications have been performed in the manuscript.

List of changes

1) The usage of the RWA approximation has been discussed and justified.
2) Some computational details have been added in section 2.
3) The reasons of the discrepancy between TLS and ab initio results have been further investigated.
4) Minor errors have been corrected in the text.

Published as SciPost Phys. 12, 193 (2022)

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