Magnetically Enhanced Exciton-Exciton Correlations in Semiconductors

Kner, Peter; Bar-Ad, S.; Marquezini, M. V.; Chemla, D. S.; Schäfer, Wilfried

doi:10.1103/physrevlett.78.1319

Cited by 117 publications

(89 citation statements)

References 24 publications

(30 reference statements)

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“…Consequently, the observation of quantum-beat-like behavior suggests a correlation beyond the Hartree-Fock limit. Our measurements are consistent with other [56,74,83] recent observations.…”

supporting

confidence: 94%

“…More recently, the influence of dynamical correlations in the screened Hartree-Fock approximation (and modifications thereof) on the ultrafast nonlinearities has been investigated [71]. On the other hand, correlations within the x (3) regime, such as biexcitonic effects, have been found to be described within the dynamics-controlled truncation scheme [72][73][74]. In general, these approaches require lengthy numerical solutions, and analytic solutions are not possible.…”

Section: Phenomenological Inclusion Of Many-body Contributionsmentioning

confidence: 99%

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(11 IOTA)-Oriented Heterostructures and Devices: The Effects of Strain and Orientation

Smirl¹

2001

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supporting

confidence: 94%

Section: Phenomenological Inclusion Of Many-body Contributionsmentioning

confidence: 99%

(11 IOTA)-Oriented Heterostructures and Devices: The Effects of Strain and Orientation

Smirl¹

2001

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“…Although the mean-®eld theory has enjoyed considerable success at moderate and high densities, recent studies in regimes of low excitation and very short timescale show that the behaviour of semiconductors is even more complex 6,7 . In these regimes one can probe timescales shorter than the time between quasiparticle collisions so that there are not enough scattering events over the time span of an experiment to establish the mean-®eld conditions.…”

mentioning

confidence: 99%

“…Many-particle correlation functions appear in almost all theoretical approaches for describing condensed matter; however, it is usually extremely dif®cult to access these quantities experimentally. These recent studies 6,7 allow for the ®rst time the direct investigation of high-order correlations. We will discuss the new insights into many-body physics provided by such experiments.…”

mentioning

confidence: 99%

Many-body and correlation effects in semiconductors

Chemla

Shah²

2001

Nature

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333

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Solids consist of 10 22 ±10 23 particles per cubic centimetre, interacting through in®nite-range Coulomb interactions. The linear response of a solid to a weak external perturbation is well described by the concept of non-interacting`quasiparticles' ®rst introduced by Landau. But interactions between quasiparticles can be substantial in dense systems. For example, studies over the past decade have shown that Coulomb correlations between quasiparticles dominate the nonlinear optical response of semiconductors, in marked contrast to the behaviour of atomic systems. These Coulomb correlations and other many-body interactions are important not only for semiconductors, but also for all condensed-matter systems.O ne of the most fascinating properties of quantum mechanical systems is that they can be in entangled states, that is, a coherent superposition of eigenstates unknown in classical systems. Entangled states have been observed in atomic physics, but they remain elusive in condensed matter. The primary dif®culty is that they survive only as long as the coherence is maintained, and numerous processes conspire to produce decoherence, dephasing and relaxation on an extremely short timescale (,10 -12 s) in condensed matter, which is typically composed of 10 22 ±10 23 particles cmthat interact through the in®nite-range Coulomb force. The complexity of the problem makes any theoretical approach extremely dif®cult. About ®ve decades ago, Landau proposed that real particles, strongly interacting among themselves but evolving in the real vacuum, be mapped onto`quasiparticles' . The quasiparticles arè dressed' by a part of the interaction, and are relatively long-lived excitations of the many-body system evolving in a`new vacuum' that consists of the`rest' of the many-body system and the part of the Coulomb interaction not accounted for in the quasiparticles. The quasiparticles are complex objects (Cooper pairs in a superconductor, excitons in a semiconductor, and so forth), and the new vacuum itself can be structured (it can have an antiferromagnetic order in the copper oxides) and dynamical (it can sustain phonons and magnons). For many solids, the concept of quasiparticles has been very useful for describing the ground state and small departures from it, that is, the most basic excitation and the linear response to weak external perturbations. However, the part of the Coulomb forces not accounted for in the formation of quasiparticles leads to interactions between these quasiparticles, inducing nonlinearities and destroying their phase coherence. Scientists interested in the linear response of a many-body system like to call these interactions`residual' . They are, however, not small, as shown below. They are residual only in the sense that we do not know (yet) how to treat them correctly. Understanding the in¯u-ence of these many-body interactions and Coulomb correlations is one of the central challenges of condensed-matter physics. Semiconductors form an ideal laboratory for quantitatively investigating the role of Co...

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“…The neglected genuine many-body correlation [17] may lead to almost instantaneous decay in time-integrated (TI) FWM signals, which is irrelevant to the intrinsic dephasing [5]. This effect is crucial for the magneto-confined FR [5] due to the magnetic field-induced enhancement of many-body correlation [18], but is less important for the decay of TI-FWM signals in biased SSL's, which is, in essence, an intrinsic dephasing process [3,19].…”

mentioning

confidence: 99%

Dynamic Fano resonance of Floquet-state excitons in superlattices

Liu

Zhu

2000

J. Phys.: Condens. Matter

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The dynamic Fano resonance (DFR) between discrete quasienergy excitons and sidebands of their ionization continua is predicted and investigated in dc-and ac-driven semiconductor superlattices. This DFR, well controlled by the ac field, delocalizes the excitons and opens an intrinsic decay channel in nonlinear four-wave mixing signals.PACS numbers: 71.35. Cc, 42.50.Md, 78.20.Jq, 78.47.+p The Fano resonance (FR) results from quantum coupling between a discrete state and a degenerate continuum of states and manifests itself in optical spectra as asymmetric lineshape [1]. FR was observed in a variety of atomic and molecular systems. Recently, this phenomenon has been reported in semiconductor quantum wells [2], in biased semiconductor superlattices (SSL's) [3], and in bulk GaAs in the presence of magnetic field [4,5] where discrete excitons couple to continua of the lower transitions through Coulomb interaction [6]. In addition to the frequency-domain experiments, transient four-wave mixing (FWM) in magneto-confined bulk semiconductors [5] and in SSL's [3] has demonstrated that the FR is a fundamental type of dephasing mechanism in irreversible quantum dynamical processes.An intense ac field, e.g. the free electron laser, can induce the dynamical localization (DL) [7] of electrons in SSL's. The DL is directly related to the collapse of the quasienergy band of Floquet states [8][9][10], the temporal analogue to the Bloch states in spatially periodic potential [11]. Research taking into account Coulomb interaction has shown that the DL may cause the dimension crossover of excitons [12] and the enhancement of exciton binding and opacity in linear [12,13] and nonlinear spectra [14]. Meanwhile the dynamical delocalization (DDL) effect of an ac field is also investigated on localized Wannier-Stark (WS) states [15] in biased SSL's [9,10,14], which is hindered by Coulomb binding [14].In this Letter, we predict the dynamic Fano resonance (DFR) between quasienergy exciton states in biased SSL's driven by an intense THz-field. In particular, the novelty of this DFR consists in the coupling between the discrete quasienergy exciton and the neighbor sideband of its ionization continuum. This DFR will also lead to the dynamical ionization of bound excitons in SSL's, which itself is a new effect of the ac field.The one-dimensional tight-binding model [14,16] is adopted in the present investigation. With excluding the realistic three-dimensional excitonic motion, the results are hardly compared to experimental data quantitatively, but we believe this simple model does present qualitatively correct results, in view of the fact that the ground WS exciton-state usually possesses much larger oscillator strength than its ionization continuum of inplane motion, and the coupling induced by the ac field between the in-plane motion associated with different WS states is negligible because of their approximate orthogonality. The Coulomb interaction is treated on the basis of Hartree-Fock approximation. The neglected genuine many-body corr...

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Magnetically Enhanced Exciton-Exciton Correlations in Semiconductors

Cited by 117 publications

References 24 publications

(11 IOTA)-Oriented Heterostructures and Devices: The Effects of Strain and Orientation

(11 IOTA)-Oriented Heterostructures and Devices: The Effects of Strain and Orientation

Many-body and correlation effects in semiconductors

Dynamic Fano resonance of Floquet-state excitons in superlattices

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