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Spontaneous emission

About: Spontaneous emission is a research topic. Over the lifetime, 12855 publications have been published within this topic receiving 323684 citations.


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TL;DR: In this article, a quantum-electrodynamic theory of spontaneous emission in presence of dielectrics and conductors is developed, which makes use of the master-equation techniques and the response function formalism.
Abstract: A quantum-electrodynamic theory of spontaneous emission in presence of dielectrics and conductors is developed. The theory makes use of the master-equation techniques and the response-function formalism of part I of this series of papers. Various observable entities such as damping coefficients (lifetimes), Lamb shifts, and frequency shifts are related to the appropriate surface-dependent response functions. The results are valid for arbitrary geometries (involving linear dielectrics) and naturally contain, as a special case, the usual results of spontaneous emission in free space. As explicit examples we consider a two-level atom (also the multilevel atom) in presence of a plane dielectric interface and between two conducting plates. Formulas for the shifts and widths are given and their asymptotic behavior for large and short distances is discussed. The behavior when the atom is embedded inside the dielectric is different than when the atom is outside the dielectric. The origin of coherence in the present model is discussed and the coherence effects in this model are contrasted with those in Dicke's model. The results are also compared with those obtained by the image method. Exact expressions for the operator radiation-reaction fields are obtained in terms of the atomic polarization operators and response functions. Approximate results for such fields are also given. The far-zone behavior of the radiation fields is obtained in terms of response functions and the polarization operators. Some of the normally ordered correlation functions are also calculated. The connection of some of the theoretical results with a recent experimental work of Carniglia, Mandel, and Drexhage is discussed. The effect of anisotropy of the dielectric function on the lifetimes as well as on the far-field correlation functions is also considered. Finally the contribution to the shifts and widths due to the excitation of surface polariton modes is computed and the results are compared with those obtained by the quantization of surface polariton field. It is found that such surface modes contribute significantly to widths.

150 citations

Journal ArticleDOI
TL;DR: The effects of spatial inhomogeneity, nonradiative decay, and transition dipole orientations on the observed inhibition in the band gap are discussed.
Abstract: We present time-resolved emission experiments of semiconductor quantum dots in silicon 3D inverse-woodpile photonic band gap crystals. A systematic study is made of crystals with a range of pore radii to tune the band gap relative to the emission frequency. The decay rates averaged over all dipole orientations are inhibited by a factor of 10 in the photonic band gap and enhanced up to 2× outside the gap, in agreement with theory. We discuss the effects of spatial inhomogeneity, nonradiative decay, and transition dipole orientations on the observed inhibition in the band gap.

150 citations

Journal ArticleDOI
TL;DR: In this paper, it was shown explicitly how, at high power, both the laser field and the laser noise source become classical and that the increase in noise in lasers with open cavities is not due to enhanced spontaneous emission as once thought, but to single-pass amplification.
Abstract: The basic equations governing noise phenomena are derived from first principles and applied to examples in optical communications. Quantum noise arises from two sources, the momentum fluctuations of electrons at optical frequencies and the uncertainty-related fluctuations of the electromagnetic field. Shot noise results from the beating of the noise sources with the signal field. In high-gain amplifiers, the spontaneous-emission noise dominates shot noise and results in a noise figure of at least 3 dB. It is shown explicitly how, at high power, both the laser field and the laser noise source become classical. The increase in noise in lasers with open cavities is not due to enhanced spontaneous emission as once thought, but to single-pass amplification. The noise fields and spontaneous currents have Gaussian distributions, while nonlasing modes have exponential photon-number distributions. Low-frequency intensity fluctuations arise from the electric current driving the laser and can be sub-Poissonian, in contrast to shot noise, which has a Poissonian distribution. The calculational tools are a wave equation for the field operator and a rate equation for the carrier-number operator, each containing spontaneous current noise sources. The correlation functions of these sources are determined by the fluctuation-dissipation theorem. [S0034-6861(96)00503-X]

150 citations

Journal ArticleDOI
TL;DR: In this paper, a heterogeneous quantum-cascade structure based on two bound-to-continuum designs emitting at 9.6 and 8.4μm is presented, and the spontaneous emission spectrum at room temperature has a full width at half maximum of 350 cm−1 and shows a variation of intensity of less than 20% over more than 200cm−1.
Abstract: A heterogeneous quantum-cascade structure based on two bound-to-continuum designs emitting at 9.6 and 8.4μm is presented. Its spontaneous emission spectrum at room temperature has a full width at half maximum of 350cm−1 and shows a variation of intensity of less than 20% over more than 200cm−1. External cavity lasers using a grating in Littrow configuration and antireflection coated chips with this active region could be tuned over 265cm−1 from 8.2to10.4μm, that is, over 24% of the center wavelength.

150 citations

Journal ArticleDOI
TL;DR: Single-qubit operations on a trapped atom hyperfine qubit are demonstrated using a single ultrafast pulse from a mode-locked laser, demonstrating that this interaction takes place deep within the strong excitation regime.
Abstract: We demonstrate single-qubit operations on a trapped atom hyperfine qubit using a single ultrafast pulse from a mode-locked laser. We shape the pulse from the laser and perform arotation of the qubit in less than 50 ps with a population transfer exceeding 99% and negligible effects from spontaneous emission or ac Stark shifts. The gate time is significantly shorter than the period of atomic motion in the trap (� Rabi=� trap > 10 4 ), demonstrating that this interaction takes place deep within the strong excitation regime.

150 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202383
2022213
2021360
2020338
2019419
2018453