Gauge covariances and nonlinear optical responses
| Autor: | J. M. B. Lopes dos Santos, J. M. Viana Parente Lopes, G. B. Ventura, D. J. Passos, Nuno M. R. Peres |
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| Přispěvatelé: | Universidade do Minho |
| Rok vydání: | 2017 |
| Předmět: |
Physics
Science & Technology Condensed matter physics Ciências Naturais::Ciências Físicas Ciências Físicas [Ciências Naturais] Library science FOS: Physical sciences 02 engineering and technology 021001 nanoscience & nanotechnology 01 natural sciences Condensed Matter - Other Condensed Matter Nonlinear optical Gauge (instrument) 0103 physical sciences European commission Nonlinear Optics Graphene 010306 general physics 0210 nano-technology Other Condensed Matter (cond-mat.other) |
| Zdroj: | Repositório Científico de Acesso Aberto de Portugal Repositório Científico de Acesso Aberto de Portugal (RCAAP) instacron:RCAAP |
| DOI: | 10.48550/arxiv.1703.07796 |
| Popis: | The formalism of the reduced density matrix is pursued in both length and velocity gauges of the perturbation to the crystal Hamiltonian. The covariant derivative is introduced as a convenient representation of the position operator. This allow us to write compact expressions for the reduced density matrix in any order of the perturbation which simplifies the calculations of nonlinear optical responses; as an example, we compute the first and third order contributions of the monolayer graphene. Expressions obtained in both gauges share the same formal structure, allowing a comparison of the effects of truncation to a finite set of bands. This truncation breaks the equivalence between the two approaches: its proper implementation can be done directly in the expressions derived in the length gauge, but require a revision of the equations of motion of the reduced density matrix in the velocity gauge. The work of G.B.V. and D.J.P. is supported by Fundação para a Ciência e Tecnologia (FCT) under the Grants No. PD/BI/129220/2017 and No. PD/BD/135019/2017, respectively. N.M.R.P. acknowledges funding from the European Commission within the project "Graphene-Driven Revolutions in ICT and Beyond" (Ref. No. 696656) and the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Financing Grant No. UID/FIS/04650/2013. info:eu-repo/semantics/publishedVersion |
| Databáze: | OpenAIRE |
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