Subpicosecond plasmon response: Buildup of screening

Sayed, K. El; Schuster, S.E.; Haug, H.; Peters, Frank; Henneberger, K.

doi:10.1103/physrevb.49.7337

Cited by 85 publications

(56 citation statements)

References 18 publications

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“…Signatures of non-Markovian effects have been investigated for the interaction of carriers with LO-phonons 13,14 . Furthermore, the built-up of screening has been studied on the basis of a quantum-kinetic description using the GKBA 15,16 and included in scattering calculations 17,18 . Results of the one-and two-time formulation have been compared for early times addressing the carrier-carrier scattering 10 as well as the interaction of carriers with LO-phonons 19 .…”

Section: Introductionmentioning

confidence: 99%

Relaxation properties of the quantum kinetics of carrier–LO-phonon interaction in quantum wells and quantum dots

2006

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The time evolution of optically excited carriers in semiconductor quantum wells and quantum dots is analyzed for their interaction with LO-phonons. Both the full two-time Green's function formalism and the one-time approximation provided by the generalized Kadanoff-Baym ansatz are considered, in order to compare their description of relaxation processes. It is shown that the twotime quantum kinetics leads to thermalization in all the examined cases, which is not the case for the one-time approach in the intermediate-coupling regime, even though it provides convergence to a steady state. The thermalization criterion used is the Kubo-Martin-Schwinger condition.

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Section: Introductionmentioning

confidence: 99%

Relaxation properties of the quantum kinetics of carrier–LO-phonon interaction in quantum wells and quantum dots

2006

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“…Although this approximation is standard for the linear absorption case, its justification for the transient spectra requires more attention. Indeed, the characteristic time for screening buildup is of the order Ω −1 p , where Ω p is the typical plasma frequency corresponding to the FS [166,167,163]. This time is however shorter than the typical pump duration ∼ 100fs and dephasing time (which is of the order of ps near the Fermi energy [76]), so the Coulomb interactions can be considered screened also for the nonlinear absorption case.…”

Section: Description Of the Electron-hole Pair Dynamicsmentioning

confidence: 99%

Many-body correlation effects in the ultrafast non-linear optical response of confined Fermi seas

Perakis

Shahbazyan

2000

Surface Science Reports

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The dynamics of electrons and atoms interacting with intense and ultrashort optical pulses presents an important problem in physics that cuts across different materials such as semiconductors and metals. The currently available laser pulses, as short as 5 fs, provide a time resolution shorter than the dephasing and relaxation times in many materials. This allows for a systematic study of many-body effects using nonlinear optical spectroscopy. In this review article, we discuss the role of Coulomb correlations in the ultrafast dynamics of modulation-doped quantum wells and metal nanoparticles. We focus in particular on the manifestations of non-Markovian memory effects induced by strong electron-hole and electron-plasmon correlations.

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“…Due to Rabi oscillations it is a nontrivial function of the laser pulse. If the pulse is short compared to the formation of the collective mode, all details of the density build-up become unimportant and we can approximate the time dependence of the density by a step function [15]. Then the plasma frequency is ω p (t) = ω p Θ(t − t 0 ), where t 0 is the time when the pulse reaches its maximum.…”

Section: (T T − T ) (15)mentioning

confidence: 99%

“…[15]. It is worth noting that Wigner's form of the Fourier transform (12) would just result in a factor of two in the time evolution of the dielectric function.…”

Section: (T T − T ) (15)mentioning

confidence: 99%

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Femtosecond formation of collective modes due to mean-field fluctuations

2005

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Starting from a quantum kinetic equation including the mean field and a conserving relaxationtime approximation we derive an analytic formula which describes the time dependence of the dielectric function in a plasma created by a short intense laser pulse. This formula reproduces universal features of the formation of collective modes seen in recent experimental data of femtosecond spectroscopy. The presented formula offers a tremendous simplification for the description of the formation of quasiparticle features in interacting systems. Numerical demanding treatments can now be focused on effects beyond these gross features found here to be describable analytically.PACS numbers: 71.45. Gm, 78.47.+p, 42.65.Re, 82.53.Mj The last ten years have been characterized by an enormous activity about ultrafast excitations in semiconductors, clusters, or plasmas by ultrashort laser pulses. The femtosecond spectroscopy has opened the exciting possibility to observe directly the formation of collective modes and quasiparticles in interacting many-body systems. This formation is reflected in the time dependence of the dielectric function [1, 2, 3] or terahertz emission [4]. For an overview over theoretical and experimental work see [5,6]. Such ultrafast excitations in semiconductors have been satisfactorily described by calculating nonequilibrium Green's functions [7,8]. This approach allows one to describe the formation of collective modes [3,9] and even exciton population inversions [10].The experimental data in semiconductors like GaAs [2] or InP [3] reveal similar features. These features are explained by several numerically demanding calculations. Since some common features are robust, i.e., independent of the actual used material parameters, it should be possible to describe them by a simple theory. The origin of such robust features likely rests in the short-or transienttime behavior itself. At short times higher-order correlations have no time yet to develop, therefore the dynamics is controlled exclusively by mean-field forces.Based on the mean-field character of the short-time evolution we intend to derive a time-dependent response function from the mean-field linear response. We will start from a conserving relaxation-time approximation which dates back to an idea of Mermin [11,12]. Our aim is a simple analytic formula suitable for fits of experimental data.The electron motion is controlled by the kinetic energŷ E, the external perturbationV ext and the induced meanfield potentialV ind . The corresponding kinetic equation for the one-particle reduced density matrixρ readṡwith the relaxation time τ and a local equilibrium density matrixρ l.e. determined in the following. We will calculate the response in the momentum representationwhere |p is an eigenstate of momentum p. For interpretations it is more convenient to transform the reduced density matrix to the Wigner distribution in phase spacewhere R is the spatial coordinate. The relaxation process in Eq.(1) tends to establish a local equilibrium. Following Mermin...

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Subpicosecond plasmon response: Buildup of screening

Cited by 85 publications

References 18 publications

Relaxation properties of the quantum kinetics of carrier–LO-phonon interaction in quantum wells and quantum dots

Relaxation properties of the quantum kinetics of carrier–LO-phonon interaction in quantum wells and quantum dots

Many-body correlation effects in the ultrafast non-linear optical response of confined Fermi seas

Femtosecond formation of collective modes due to mean-field fluctuations

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