Quantum theory of light emission from a semiconductor quantum dot

Feldtmann, T.; Schneebeli, L.; Kira, M.; Koch, Stefan

doi:10.1103/physrevb.73.155319

Cited by 51 publications

(33 citation statements)

References 47 publications

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“…Microscopic models that take into account the exact band structure and many-body interactions [CHO03,ROD05a,FEL06a,GIE07] can describe the complex energy structure of quantum dots very realistically, but these approaches are too complicated to be applied in dynamic problems. On the other hand, simple rateequation models exist [NAD09,ASR10,ERN10a] that can be easily implemented and require little computation power, and often allow for analytical treatment.…”

Section: Introductionmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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In this thesis the dynamics and performance of optoelectronic devices based on semiconductor quantum-dots are investigated.In the first part, the dynamics of quantum-dot lasers under external perturbations is discussed. Using a microscopically based balance equation model that incorporates detailed charge-carrier scattering dynamics and the possibility to describe nonequilibrium between intra-band electronic states, the relaxation oscillations of the quantum-dot laser are investigated. Three qualitatively different dynamic regimes are identified in dependence of the scattering rates -the "constantreservoir" regime for slow scattering, the "overdamped" regime, and the "synchronized" regime for high scattering -characterized by a varying degree of nonequilibrium between the quantum-dot and reservoir states.Important differences to conventional lasers are found in the modulation response and the dynamics in optical injection and feedback setups. Common theoretical models and approaches used to describe these applications are shown to yield inaccurate predictions, especially in the "constant-reservoir" and "overdamped" dynamic regimes. An important consequence is that the amplitude-phase coupling in quantum-dot lasers, commonly described by the α-factor, differs from conventional descriptions due to the desynchronization of gain and refractive index. While the α-factor describes bifurcations of fixed points accurately, it fails in describing dynamic solutions and overestimates the extent of complex dynamics. The observed low sensitivity to optical perturbations in quantum-dot lasers can therefore be attributed partly to the charge-carrier nonequilibrium. Three quantum-dot laser models on different levels of sophistication are presented that can accurately describe the quantum-dot nonequilibrium dynamics.In the second part of the thesis, the performance of quantum-dot semiconductor optical amplifiers is investigated, and two types of applications unique to quantum-dots as active medium are discussed. The ground and excited states of the quantum-dots allow an ultra-broad-band amplification of optical data streams. Amplified signals on the ground-state frequencies are shown to generally exhibit higher quality than on the excited state, due to a lower sensitivity of the groundstate to carrier-density variations. Nevertheless the quantum-dot amplifier is found to allow effective amplification on both frequency ranges. Furthermore, a parameter range is identified that allows for a simultaneous amplification of data signals on the ground and excited state in a counter-propagating setup.The long microscopically polarization dephasing times in quantum-dots are found to enable quantum-coherent interactions on a macroscopic scale at room-temperature. By comparison with experiments, the occurrence of Rabi-oscillations by amplification of ultra-short pulses is demonstrated. Quantum-dot based devices could therefore be used for future applications based on quantum-coherent effects.

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Section: Introductionmentioning

confidence: 99%

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Lingnau

2015

Springer Theses

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“…Due to the three-dimensional confinement, the QD electrons occupy a discrete set of states which couple to each other and to a continuum of WL states via the Coulomb, phonon, and light-matter interactions, yielding a complicated many-body problem [14,15,16,17]. For strongcoupling investigations, one typically studies strongly confining dots where only one discrete electron and hole level -constituting an effective two-level system -couples to the cavity resonance.…”

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confidence: 99%

“…The light field corresponding to a mode function u q (r) is quantized by introducing the Bosonic operatorB q where q is the wave vector of light outside the cavity. The system Hamiltonian for the investigated dots and its interaction with light follows then from [17,18] …”

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confidence: 99%

Characterization of Strong Light-Matter Coupling in Semiconductor Quantum-Dot Microcavities via Photon-Statistics Spectroscopy

2008

Self Cite

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It is shown that spectrally resolved photon-statistics measurements of the resonance fluorescence from realistic semiconductor quantum-dot systems allow for high contrast identification of the twophoton strong-coupling states. Using a microscopic theory, the second-rung resonance is analyzed and optimum excitation conditions are determined. The computed photon-statistics spectrum displays gigantic, experimentally robust resonances at the energetic positions of the second-rung emission.PACS numbers: 42.50. Pq, 42.50.Ar, 78.67.Hc, 78.90.+t Even though light-quantization effects, such as squeezing [1], antibunching [2], and entanglement [3], have been observed under a wide range of conditions, one can rarely detect the discrete energy levels of the different photonnumber states directly as resonances. Under strongcoupling conditions between a two-level resonance at the energy ω and the quantized resonant light field, the resulting dressed-state resonances appear at ωn±g √ n + 1 where n is the occupation of the photon-number state |n and g is the light-matter coupling constant [4]. The resulting discrete energy structure resembles a ladder with n-dependent rungs. The first rung shows the so-called vacuum Rabi splitting 2g, the second rung shows the splitting 2g √ 2, and so on. For sufficiently small damping and dephasing, the different rungs are clearly visible as discrete resonances, e.g., in transmission spectra.The first observations of strong coupling [5,6] and the second rung [7] were reported for atoms in high-quality cavities. Besides the demonstration of the discrete nature of light, this research has lead to major advances, e.g. in utilizing entanglement effects as a basis for quantum-logic applications [8,9]. The clear identification of the secondrung resonance can be considered as the critical step if one wants to use other materials, such as solid-state systems for strong-coupling applications. A promising candidate are semiconductor quantum dots (QD) in microcavities. Recent experiments [10,11,12,13] have already demonstrated that one can see clear vacuum Rabi splitting effects in the photoluminescence (PL) of such systems. However, despite continuing attempts, the second rung resonance has not yet been observed. The most likely reason for this failure is that dephasing and the other broadening effects in the real systems smear out the expected discrete features.In this Letter, we propose a novel scheme to observe the second-rung strong coupling effects even under the realistic broadening conditions of the currently available samples. In our approach, we use a fully microscopic theory to determine the exact conditions to obtain unambiguous evidence for the presence of the second-rung resonance in QD microcavities. Our results confirm the difficulty of the second-rung observations in standard semiconductor experiments that monitor PL after carrier capture of electrons, initially created to the wetting layer. However, we demonstrate that it should be completely feasible to observe the second rung in re...

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“…For this case the SLE had been extended by including the optical modes of the micropillar. The SLE have been formulated also for semiconductor QDs [103,104]. This microscopic semiconductor theory explains important deviations from the "artificial atom" picture [105,106].…”

Section: Theorymentioning

confidence: 99%

Properties and prospects of blue–green emitting II–VI‐based monolithic microcavities

Sebald

Kruse

Wiersig

2009

Physica Status Solidi (b)

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1 Introduction In the last years new ways to manipulate the light-matter interaction were found by modifying photonic components which confine light on the wavelength scale by means of semiconductor microcavities (MCs) [1]. The modified optical density of states produced by photonic structuring allows emission and absorption rates to be enhanced or suppressed. This is known as the Purcell effect which can be used to control the spontaneous emission [2]. Semiconductor MCs appear to a be highly attractive systems for the realization of a new generation of optoelectronic devices, polariton devices, optical switches and spin-memory elements. Several types of solid state MCs [1], including micropillars [3,4], microdisks [5,6] and photonic crystals [7,8], offer very small mode volumes V in combination with high quality factors Q. These factors describe the ability of the cavity to confine the light.

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Quantum theory of light emission from a semiconductor quantum dot

Cited by 51 publications

References 47 publications

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Nonlinear and Nonequilibrium Dynamics of Quantum-Dot Optoelectronic Devices

Characterization of Strong Light-Matter Coupling in Semiconductor Quantum-Dot Microcavities via Photon-Statistics Spectroscopy

Properties and prospects of blue–green emitting II–VI‐based monolithic microcavities

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