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Higher harmonic generation in plane graphene quantum dots initiated by intense coherent radiation is investigated, using dynamical Hartree-Fock mean-field theory. A microscopic theory describing the extreme nonlinear optical response of…

Mesoscale and Nanoscale Physics · Physics 2022-05-11 B. R. Avchyan , A. G. Ghazaryan , K. A. Sargsyan , Kh. V. Sedrakian

The disclosure of basic nonlinear optical properties of graphene-like nanostructures with correlated electron-hole nonlinear dynamics over a wide range of frequencies and pump field intensities is of great importance for both graphene…

Mesoscale and Nanoscale Physics · Physics 2022-06-15 H. K. Avetissian , S. S. Israelyan , H. H. Matevosyan , G. F. Mkrtchian

Generation of high harmonics in a monolayer graphene initiated by strong coherent radiation field, taking into account electron-electron Coulomb interaction is investigated. A microscopic theory describing the nonlinear optical response of…

Mesoscale and Nanoscale Physics · Physics 2018-04-04 H. K. Avetissian , G. F. Mkrtchian

The multiphoton excitation and high harmonic generation (HHG) processes are considered using the microscopic quantum theory of nonlinear interaction of strong coherent electromagnetic (EM) radiation with rectangular graphene quantum dot…

Mesoscale and Nanoscale Physics · Physics 2023-04-26 A G Ghazaryan , Kh V Sedrakian

We present a theory of excitonic processes in gate controlled graphene quantum dots. The dependence of the energy gap on shape, size and edge for graphene quantum dots with up to a million atoms is predicted. Using a combination of…

Mesoscale and Nanoscale Physics · Physics 2015-05-19 A. D. Guclu , P. Potasz , P. Hawrylak

High-order frequency mixing in graphene using a two-color radiation field consisting of the fundamental and the second harmonic fields of an ultrashort linearly polarized laser pulse is studied. It is shown that the harmonics originated…

Mesoscale and Nanoscale Physics · Physics 2022-05-25 Hamlet K. Avetissian , Garnik F. Mkrtchian , Andreas Knorr

By a combination of Hartree-Fock simulations, exact diagonalization, and perturbative calculations, we investigate the ground-state properties of disorder-free circular quantum dots formed in a graphene monolayer. Taking the reference…

Mesoscale and Nanoscale Physics · Physics 2011-11-01 Tomi Paananen , Reinhold Egger

The optical response and the ground state of graphene and graphene-like systems are determined self-consistently. Deriving equations of motion for the basic variables, graphene Bloch equations are introduced and combined with a variational…

Materials Science · Physics 2012-01-10 T. Stroucken , J. H. Grönqvist , S. W. Koch

We investigate high-order harmonic generation (HHG) in graphene with a quantum master equation approach. The simulations reproduce the observed enhancement in HHG in graphene under elliptically polarized light [N. Yoshikawa et al, Science…

Materials Science · Physics 2021-02-03 Shunsuke A. Sato , Hideki Hirori , Yasuyuki Sanari , Yoshihiko Kanemitsu , Angel Rubio

We theoretically investigate the effects of Coulomb interaction, at the level of unscreened Hartree-Fock approximation, on third harmonic generation of undoped graphene in an equation of motion framework. The unperturbed electronic states…

Mesoscale and Nanoscale Physics · Physics 2020-01-01 J. L. Cheng , J. E. Sipe , Chunlei Guo

High-harmonic generation (HHG) in condensed-matter systems is both a source of fundamental insight into quantum electron motion and a promising candidate to realize compact ultraviolet and ultrafast light sources. Here we argue that the…

Mesoscale and Nanoscale Physics · Physics 2017-03-08 Joel D. Cox , Andrea Marini , F. Javier García de Abajo

Linear and nonlinear optical properties of low dimensional nanostructures have attracted a large interest in the scientific community as tools to probe the strong confinement of the electrons and for possible applications in optoelectronic…

Materials Science · Physics 2017-03-08 C. Attaccalite , E. Cannuccia , M. Grüning

he properties of excitons formed in spherical quantum dots are studied using the $\mathbf{k}\cdot\mathbf{p}$ method within the Hartree approximation. The spherical quantum dots considered have a central core and several concentric layers of…

Mesoscale and Nanoscale Physics · Physics 2019-10-11 Mariano Garagiola , Omar Osenda

Excitonic contributions to absorption and photocurrent generation in semiconductor nanostructures are described theoretically and simulated numerically using steady-state non-equilibrium Green's function theory. In a first approach, the…

Mesoscale and Nanoscale Physics · Physics 2012-09-28 U. Aeberhard

We study the effect of electron-electron interactions in the optical conductivity of graphene under applied bias and derive a generalization of Elliot's formula, commonly used for semiconductors, for the optical intensity. We show that {\it…

Mesoscale and Nanoscale Physics · Physics 2010-07-29 N. M. R. Peres , R. M. Ribeiro , A. H. Castro Neto

We develop an ab initio framework that captures the impact of electron-electron and electron-hole interactions on phonon properties. This enables the inclusion of excitonic effects in the optical phonon dispersions and lifetimes of…

Materials Science · Physics 2025-06-17 Alberto Guandalini , Francesco Macheda , Giovanni Caldarelli , Francesco Mauri

We investigate the effect of phenomenological relaxation parameters on the third order optical nonlinearity of doped graphene by perturbatively solving the semiconductor Bloch equation around the Dirac points. An analytic expression for the…

Materials Science · Physics 2015-12-24 J. L. Cheng , N. Vermeulen , J. E. Sipe

We study the energy of quasi-particles in graphene within the Hartree-Fock approximation. The quasi-particles are confined via an inhomogeneous magnetic field and interact via the Coulomb potential. We show that the associated functional…

Mesoscale and Nanoscale Physics · Physics 2010-05-07 R. Egger , A. De Martino , H. Siedentop , E. Stockmeyer

We study the linear optical absorption of bulk semiconductors in the presence of a homogeneous constant (dc) electric field with an approach suitable for including excitonic effects while working with many-band models. The absorption…

Mesoscale and Nanoscale Physics · Physics 2015-06-19 Federico Duque-Gomez , J. E. Sipe

We report calculations of the high harmonic generation spectra of the C\textsubscript{60} fullerene molecule, employing a diverse set of real-time time-dependent quantum chemical methods. All methodologies involve expanding the propagated…

Chemical Physics · Physics 2023-12-05 Aleksander P. Woźniak , Robert Moszyński
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