Correlation effects in high-order harmonic generation from finite systems

Hansen, Thomas; Jensen, Simon Vendelbo Bylling; Madsen, Lars Bojer

doi:10.1103/physreva.105.053118

Cited by 16 publications

(6 citation statements)

References 48 publications

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“…However, in practice, these values may change with doping level [26] or with temperatures due to the correlation effects [27,[73][74][75]. Although recently the effects of correlations on HHG beyond the phenomenological description have been attracting much interest [75][76][77][78][79][80][81][82][83][84][85][86][87][88][89][90], deeper understanding is required for further accurate understanding of the behavior of HHG. This is an important future task.…”

Section: Discussionmentioning

confidence: 99%

Doping and gap size dependence of high-harmonic generation in graphene: Importance of consistent formulation of light-matter coupling

Murakami

Schüler

2022

Phys. Rev. B

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High-harmonic generation (HHG) in solids is a fundamental nonlinear phenomenon, which can be efficiently controlled by modifying system parameters such as doping level and temperature. To correctly predict the dependence of HHG on these parameters, consistent theoretical formulation of the light-matter coupling is crucial. Recently, contributions to the current that are often missing in the HHG analysis based on the semiconductor Bloch equations have been pointed out [Wilhelm et al., Phys. Rev. B 103, 125419 (2021)]. In this paper, by systematically analyzing the doping and gap-size dependence of HHG in gapped graphene, we discuss the practical impact of such terms. In particular, we focus on the role of the current J (2) ra , which originates from the change of the intraband dipole via interband transition. When the gap is small and the system is close to half filling, intraband and interband currents mostly cancel, thus suppressing the HHG signal-an important property that is broken when neglecting J (2) ra . Furthermore, without J (2) ra , the doping and gap-size dependence of HHG becomes qualitatively different from the full evaluation. Our results demonstrate the importance of the consistent expression of the current to study the parameter dependence of HHG for the small gap systems.

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Section: Discussionmentioning

confidence: 99%

Doping and gap size dependence of high-harmonic generation in graphene: Importance of consistent formulation of light-matter coupling

Murakami

Schüler

2022

Phys. Rev. B

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“…This irregularity been seen in previous works using similar systems, e.g,. [6,21,26,33,37,67], and has been speculated to originate from limited pulse lengths and missing dephasing channels [21]. In [6], the less clear peaks at the odd harmonics were attributed to the U term.…”

Section: Spectramentioning

confidence: 99%

“…The mean-field approximation allows the electrons to be treated as independent particles, which is not exact. With that in mind, over the last 5 years, researchers have worked on the effects of beyond mean-field electron-electron interaction on HHG both theoretically [6,21,[26][27][28][29][30][31][32][33][34][35][36][37] and experimentally [38][39][40]. Much theoretical research [6,21,27,33,37,41] has used the Hubbard model, which is also used in this work.…”

Section: Introductionmentioning

confidence: 99%

“…With that in mind, over the last 5 years, researchers have worked on the effects of beyond mean-field electron-electron interaction on HHG both theoretically [6,21,[26][27][28][29][30][31][32][33][34][35][36][37] and experimentally [38][39][40]. Much theoretical research [6,21,27,33,37,41] has used the Hubbard model, which is also used in this work. This model includes electron-electron interactions through the Hubbard U, which energetically penalizes the occurrence of doubly-occupied sites.…”

Section: Introductionmentioning

confidence: 99%

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Lattice imperfections and high-harmonic generation in correlated systems

Hansen,

Bojer Madsen

2024

New J. Phys.

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We study effects of lattice imperfections on high-harmonic generation from correlated systems using the Fermi–Hubbard model. We simulate such imperfections by randomly modifying the chemical potential across the individual lattice sites. We control the degree of electron–electron interaction by varying the Hubbard U. In the limit of vanishing U, this approach results in Anderson localization. For nonvanishing U, we rationalize the spectral observations in terms of qualitative k-space and real-space pictures. When the interaction and imperfection terms are of comparable magnitude, they may balance each other out, causing Bloch-like transitions. If the terms differ significantly, each electron transition requires a relatively large amount of energy and the current is reduced. We find that imperfections result in increased high-harmonic gain. The spectral gain is mainly in high harmonic orders for low U and low orders for high U.

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“…High-harmonic generation (HHG) [1][2][3][4], i.e. the coherent production of high-energy photons by upconversion of the photon energy of the laser, represents a promising tool to probe the structure [5][6][7][8][9], topology [10][11][12][13][14][15][16], electron-correlation [17][18][19][20][21], and ultrafast electron dynamics [22][23][24] of condensed-matter systems. Recently, it has been proposed that in crystalline systems with a non-vanishing Berry curvature, a laser field can induce a nonlinear anomalous current polarized perpendicular to the laser polarization and lead to the generation of nonperturbative anomalous high harmonics [11,14,15,[25][26][27].…”

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confidence: 99%

Characterizing Anomalous High-Harmonic Generation in Solids

Yue¹,

Gaarde²

2022

Preprint

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Anomalous high-harmonic generation (HHG) arises in certain solids when irradiated by an intense laser field, as the result of a nonlinear perpendicular current akin to a Hall current. Here, we theoretically characterize the anomalous HHG mechanism, via development of an ab-initio methodology for strong-field laser-solid interaction that allows a rigorous decomposition of the total current. We identify two key characteristics of the anomalous harmonic yields: an overall increase with laser wavelength; and pronounced minima at certain intensities or wavelengths around which the emission time profiles drastically change. Such signatures can be exploited to disentangle the anomalous harmonics from the competing interband harmonics, and thus pave way for the experimental identification and time-domain control of pure anomalous harmonics.

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Correlation effects in high-order harmonic generation from finite systems

Cited by 16 publications

References 48 publications

Doping and gap size dependence of high-harmonic generation in graphene: Importance of consistent formulation of light-matter coupling

Doping and gap size dependence of high-harmonic generation in graphene: Importance of consistent formulation of light-matter coupling

Lattice imperfections and high-harmonic generation in correlated systems

Characterizing Anomalous High-Harmonic Generation in Solids

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