Quantum beats between the light and heavy hole excitons in a quantum well

Feuerbacher, B. F.; Kühl, J.; Eccleston, Richard; Ploog, K.

doi:10.1016/0038-1098(90)90992-k

Cited by 112 publications

(37 citation statements)

References 12 publications

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“…2 also shows resolved beats occurring with periods shorter by a factor 2 ±0.1, and in at present fully understood but may be related to higherorder anharmonic behavior involving the biexciton. We note that beat components with period shorter than expected appear in some earlier data, obtained from a quantum well showing some evidence for biexcitonic features in the spectral dependence of the self-diffraction efficiency [2,14].…”

Section: Two Factors Ensure That the Biexciton Population Consists Essupporting

confidence: 63%

Resonant generation of biexcitons in a GaAs quantum well

et al. 1992

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Generation of cold excitons in GaAs quantum wells is shown to lead to enhanced condensation to the biexciton state under cw illumination. Resonant two-photon absorption to the biexciton state in the same structure is found to account for a quantum beating phenomenon involving the biexciton and exciton states in a more complex three-level system than hitherto investigated.PACS numbers: 71.35. +Z, 42.50.Md, 78.47.+p, 78.55.Cr Excitons in three-dimensional materials have been known for some time to be an important paradigm for the interacting boson system, where a precursor to BoseEinstein condensation is the formation of excitonic molecules, or biexcitons [1]. Only recently has it become clear that biexcitons also play an important role in the nonlinear optical response of GaAs quantum-well structures [2]. So far, however, there has been no systematic study of the behavior of biexcitons in GaAs under the conditions of resonant excitation which are implicit in the investigation of the excitonic resonances in the third-and higher-order optical nonlinearities which mediate fourwave mixing. In order to observe biexcitonic effects in GaAs it is necessary to work with quantum wells, since in two dimensions the binding energy of the excitonic molecule is increased over the bulk value by nearly an order of magnitude, to ^ 1 meV. For material of appropriate high quality the free exciton linewidth may be reduced to 0.5 meV thus permitting the spectral resolution of the biexciton [3][4][5][6]. This narrow, largely homogeneous, linewidth also ensures that the dephasing time for the excitonic system is of the order of picoseconds, so coherent transient effects may be resolved in the time domain if light pulses of duration ~ 1 ps interact with the excitons, Recent work has indicated that biexcitons play an important role in such coherent interactions, but there has been no clear corroboration by combined time-and frequency-domain measurements. In this Letter we report optical processes dominated by biexcitons generated in both two-photon and single-photon transitions in a single GaAs quantum well, and show that the biexcitons are involved in coherent processes over a range of biexciton densities.The simplest model of an exciton in GaAs treats it as a two-level quantum system. The excitons interact little at very low densities, but as the density is increased, pairs of excitons may bind weakly together to form excitonic molecules. These biexcitons add an extra level to the twolevel scheme, at an energy 2E^ ~ Eh, where E^ is the exciton energy and Eh the binding energy of the molecule. Three-level systems recently investigated by quantumbeating spectroscopy using self-diffraction include lightand heavy-hole excitons [7], exciton transitions split by spatial variations in well thickness [8], and free and bound excitons [9]. For each of these systems the optical emission process ends with the crystal in its ground state. In the case of the system of excitons and biexcitons, the biexciton state may be reached by two-photon absorpt...

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Section: Two Factors Ensure That the Biexciton Population Consists Essupporting

confidence: 63%

Resonant generation of biexcitons in a GaAs quantum well

et al. 1992

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“…(3a). Such beating signals have been observed in earlier studies on QWs and are assigned to quantum beats between the HH and LH excitons in the quantum well 46,47 . The DR signal is fit to the following expression: 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 where Γ describes the population relaxation rate of the LH exciton, ߛ ଶଵ is the dephasing rate for the We analyze the quantum beats measured on the bare QW by fitting the data using Eq.…”

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confidence: 72%

Quantum Beats in Hybrid Metal–Semiconductor Nanostructures

et al. 2015

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We investigate non-radiative quantum coherence in the presence of coupling between excitons and surface plasmon polaritons (SPPs) in a hybrid metal-semiconductor nanostructure. In particular, we study how quantum coherence between heavy-hole (HH) and light-hole (LH) excitons in a GaAs quantum well (QW) is modified when they are coupled to SPPs of a gold grating. We find that the nonradative coherence is reduced in correlation with the coupling strength between the excitons and SPPs. Under the resonant coupling condition, the non-radiative coherence remains in the range of hundreds of femtoseconds, which is significantly longer than the plasmonic coherence. These experiments directly probe quantum dynamics in a prototypical hybrid system and provide critical information for exploring future quantum plasmonics applications.

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“…Such quantum beats have been observed in quantum wells with a frequency corresponding to the biexciton binding energy [71], and have been attributed to the simultaneous coherent excitation of bound and unbound two-exciton states. Quantum beats have also been ob-Original Paper served with a frequency corresponding to the energy difference between the light hole and heavy hole excitons in GaAs quantum wells [19,82,83].…”

Section: Discussionmentioning

confidence: 99%

Photon echo studies of biexcitons and coherences in colloidal CdSe quantum dots

Colonna¹,

Yang²,

Scholes³

2005

Physica Status Solidi (b)

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PACS 71.35.Cc, 78.47.+p, 78.67.Hc Nonlinear optical properties of colloidal quantum dots are studied to elucidate the significance and nature of many-body effects. Two-pulse photon echo studies of nanocrystalline CdSe quantum dots are reported for samples dispersed in a poly(butylmethacrylate) film (4.4 K). Oscillations are observed in the experimental data that are attributed to 3/2 1 1 e S S -3/2 2 1 e S S biexciton cohererences. Signals are simulated using a phenomenological model based on the many-body description of the dynamics (the average polarization model). It is found that the electronic coherences and the nonlinear response originating from biexciton source terms are important, but their manifestation in the photon echo signals is strongly influenced by the interplay between homogeneous and inhomogeneous line broadening.

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Quantum beats between the light and heavy hole excitons in a quantum well

Cited by 112 publications

References 12 publications

Resonant generation of biexcitons in a GaAs quantum well

Resonant generation of biexcitons in a GaAs quantum well

Quantum Beats in Hybrid Metal–Semiconductor Nanostructures

Photon echo studies of biexcitons and coherences in colloidal CdSe quantum dots

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