Coherence of Four-Particle Correlations in Semiconductors

Kner, Peter; Schäfer, Wilfried; Lövenich, R.; Chemla, D. S.

doi:10.1103/physrevlett.81.5386

Cited by 97 publications

(70 citation statements)

References 27 publications

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“…13 Furthermore, these results clearly demonstrate a correlation-induced redshift with cocircularly polarized pump and probe pulses.…”

Section: ͑6͒mentioning

confidence: 60%

“…Ultrafast time-resolved nonlinear spectroscopy has been shown to be a versatile tool for investigating many-body effects in QW's. [12][13][14] In spite of many investigations and of recent progress 7 in understanding the characteristic dynamic behavior of four-wave mixing ͑FWM͒ in SMC's, the coherent dynamics of the excitonic nonlinear response in the nonperturbative regime has not been fully understood. Detailed ultrafast time-resolved measurements on SMC's ͑Ref.…”

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confidence: 99%

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Spectroscopy of four-particle correlations in semiconductor microcavities

2001

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We present a theory of ultrafast time-resolved pump and probe spectroscopy in semiconductor microcavities. The numerical solutions are in excellent agreement with experimental data. An analytical study based on the Weisskopf-Wigner approximation gives physical insight into the transient optical nonlinearities of semiconductor microcavites. It is able to explain the physical origin of the unusual transient shifts and asymmetricexcitation-induced dephasing observed experimentally. This theory demonstrates that the nonperturbative regime provides a unique tool for measuring the spectrum of four-particle correlations. DOI: 10.1103 If one or more quantum wells ͑QW's͒ are embedded in a wavelength-scale optical cavity, the light-matter interaction enters a nonperturbative regime when the collective dipole coupling rate between the QW exciton and the cavity field exceeds the relevant decay rates.1,2 This strong light-matter coupling creates two mixed photon-exciton normal modes ͑the cavity polaritons͒. Extensive studies of semiconductor microcavities ͑SMC's͒ have shown normal mode splitting of polaritons in reflection 1 and emission spectra 3 and normal mode oscillations in transient optical response. 4 The ultrafast nonlinear optical response of SMC's has attracted growing interest for exploring fundamental lightmatter interactions in many-particle quantum systems, 5-11 as well as for future implementations of ultrafast photonic devices and of devices based on quantum correlations. Ultrafast time-resolved nonlinear spectroscopy has been shown to be a versatile tool for investigating many-body effects in QW's. [12][13][14] In spite of many investigations and of recent progress 7 in understanding the characteristic dynamic behavior of four-wave mixing ͑FWM͒ in SMC's, the coherent dynamics of the excitonic nonlinear response in the nonperturbative regime has not been fully understood. Detailed ultrafast time-resolved measurements on SMC's ͑Ref. 6͒ have shown nonlinear absorption and unusual transient Stark shifts of the polariton resonances strongly depending on the excitation energy and on the polariton branch whose origin remains unclear. A theory able to describe correctly transient optical nonlinearities of SMC's is thus required; it is also relevant for the optimization of the coherent control of polariton modes 15 and for enhancing optical nonlinearities at the same time minimizing excitation-induced dephasing ͑EID͒ for applications.In this paper we present a theory of ultrafast timeresolved pump and probe spectroscopy in the strongcoupling regime of SMC's. The theory provides physical insight into the transient optical nonlinearities of semiconductor microcavites. It is able to explain the physical origin of the transient shifts and the EID observed experimentally. It also reproduces and explains their dependence on the exciton-cavity detuning and on the pump and probe energies. One striking prediction of this theory is that when both the pump and probe are resonant with the upper polariton at zero or positive d...

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“…13 Furthermore, these results clearly demonstrate a correlation-induced redshift with cocircularly polarized pump and probe pulses.…”

Section: ͑6͒mentioning

confidence: 60%

mentioning

confidence: 99%

Spectroscopy of four-particle correlations in semiconductor microcavities

2001

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“…The experiments of the type described above provide a means of observing the effects of higher-order correlations and investigating their properties. For example, the dephasing of 4-particle correlation functions by phonons and carrier scattering has been studied recently for the ®rst time 39 .…”

Section: High-order Correlation Effectsmentioning

confidence: 99%

Many-body and correlation effects in semiconductors

Chemla

Shah²

2001

Nature

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333

304

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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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“…Biexciton effects associated with XX have been identified even in III-V semiconductors and more easily in II-VI and I-VII semiconductors. However, processes involving two excitons require obviously to take account of four-particle correlations, [1][2][3][4][5][6][7][8] which mean not only XX but also unbound biexciton (XX*). Actually, XX* can affect the observed signals strongly even under no clear signature of XX, for example, in cocircularly polarized excitation where XX cannot be created according to the polarization selection rules.…”

Section: Introductionmentioning

confidence: 99%

Exciton-exciton interaction and heterobiexcitons in GaN

et al. 2003

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The formation of not only A biexcitons (XX AA ) but also heterobiexcitons that consist of A and B excitons (XX AB ) in a free-standing bulk GaN is identified by polarization-sensitive spectrally resolved FWM measurements. The FWM spectra and delay-time dependence show that the interaction between A and B exciton gives rise to the energy shifts of the spectra and the phase shifts of the quantum beating, which is considered as the effect of the unbound state of XX AB ͑i.e., XX AB * ) and XX AB * is found to play an important role in the FWM signals for all polarizations. The unbound A biexciton (XX AA * ) is also observed clearly in spectral and temporal domains.

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Coherence of Four-Particle Correlations in Semiconductors

Cited by 97 publications

References 27 publications

Spectroscopy of four-particle correlations in semiconductor microcavities

Spectroscopy of four-particle correlations in semiconductor microcavities

Many-body and correlation effects in semiconductors

Exciton-exciton interaction and heterobiexcitons in GaN

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