Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Journal of Physics C Solid State Physics

Superradiance of excitons

Y C Lee, K C Liu

Published Apr 10, 1981• 12 citations
Publisher

Abstract

The theory of superradiance of excitons in thin crystal films is presented. While the broken crystal symmetry in the direction normal to the film plane renders the radiative decay of the exciton possible, the remaining crystal symmetry on the film leads to phase coherence between the exciton and the photon fields everywhere on the film. Consequently, a trading between the degrees of freedom of the radiation field and those of the atoms is shown to be responsible for the predicted superradiative enhancement of the exciton decay by a factor ( lambda /d) 2 >>1 in the optical region.

DOI
10.1088/0022-3719/14/10/006

Related papers

Renormalized frequency shift of superradiant excitons in thin semiconductor films

Yung-Chang Lee, Der-San Chuu, Wai‐Ning Mei

The radiative frequency shift of an exciton in a thin semiconductor film, like its radiative level width, is shown to be superradiatively enhanced. Unlike the latter, however, a finite frequency shift can only be obtained after proper renormalization for the correlated system. The shift is found to be inversely proportional to the square of the factor ${\mathit{k}}_{0}$d and proportional to the film thickness T, ${\mathit{k}}_{0}$=${\mathit{E}}_{\mathbf{q}\mathit{n}}$/\ensuremath{\Elzxh}c, ${\mathit{E}}_{\mathbf{q}\mathit{n}}$ being the exciton energy gap and d the lattice constant of the semiconductor. Therefore, the coherent frequency shift can be observed experimentally if one varies the thickness, or the exciton energy gap ${\mathit{E}}_{\mathbf{q}\mathit{n}}$ by imposing high pressure.

Physical Review Letters•Aug 17, 1992•9 citations

Superradiance and subradiance in systems of excited nuclei

Tian-Xiang Shen

This thesis studies superradiance and subradiance in the normal modes of excitation of systems of resonant nuclei. The nuclei are treated as classical electric dipole oscillators interacting through their radiation fields. This coupling radically alters the radiative decay of the system relative to the decay of an isolated nucleus, and leads to both superradiant and subradiant states with strongly enhanced or suppressed radiative decay rates, and with normal mode frequencies which can be strongly shifted from the natural resonance frequency. This issue is of considerable current interest because it is now possible to create spatially coherent single exciton nuclear states by illuminating crystals containing resonant Mossbauer nuclei with synchrotron radiation pulses. The purpose of this thesis is to solve for the radiative eigenmodes in a system of nuclei and to investigate superradiance and subradiance both in the eigenmode solutions and in the synchrotron radiation produced nuclear exciton state.

•Jan 1, 1991•2 citations

Wannier exciton superradiance in a quantum-well microcavity

Gunnar G. Bjork, Stanley Pau, Joseph M. Jacobson +1 more

Excitonic superradiance has been predicted to induce a rapid decay rate of coherently excited excitons in thin quantum wells and microspheres. In this paper we revisit this problem and derive the enhancement factor of the radiative decay due to superradiant effects. In a GaAs quantum well, the excitonic superradiant radiative decay can be roughly 320 times faster than the decay of a free electron-hole pair. The exciton decay rate depends strongly on the lateral size of the wave function when the size is smaller than the inverse of the wave vector of the emitted light. In a GaAs quantum well this corresponds to a distance of \ensuremath{\approxeq}365 \AA{}. Therefore, it is predicted that localization and elastic phonon scattering may lead to decay rates substantially smaller than that predicted for an ideal quantum well. It is also shown that if the quantum well is placed inside a microcavity, the decay rate can be enhanced even further since the cavity modifies the available density of radiation states in a way that matches the superradiant emission. It is predicted that in a matched dielectric cavity the decay rate can be enhanced by an additional factor of 100, but that inhomogeneous broadening may in practice limit the possible enhancement.

Physical review. B, Condensed matter•Dec 15, 1994•63 citations

Enhanced Radiative Decay and Optical Dephasing of Excitons in GaAs Quantum Well Bragg Structures

J. Kühl, Matthias Hübner, T. Stroucken +4 more

Rapid superradiant decay of coherently excited excitons in thin quantum wells (QWs) on a time scale of approximately 10 ps has been theoretically predicted by several groups [1], however, the experimental observation of this ultrafast radiative recombination is still the subject of controversial discussions. A recent theoretical paper [2] concludes, that this radiative decay rate should be strongly enhanced in multiple QW (MQW) Bragg structures due to radiative coupling of excitons excited in different wells via the exchange of transverse photons.

International Conference on Ultrafast Phenomena•Jan 1, 1996•0 citations

Superradiative decay and enhanced optical nonlinearity of low-dimensional excitons

Eiichi Hanamura

We want to make the best use of the mesoscopic or macroscopic transition dipolemornent of excitons by controling the size and dimension of the materials. First, the semiconductor microcrystallites embedded in insulators or glasses are shown to have the mesoscopic transition dipolemoment of excitons1 . As a result, the exciton in CuC1 microcrystallite with the radius 80 A superradiatively decays in 100 pico-second2. Futhermore, the exciton-exciton interaction and the decay and relaxation of the exciton work effectively in deviating the excitons in the microcrystallite from ideal bosons and this system shows the large third-order optical susceptibility"3 of an order of iO esu when we assume the 0.1% packing of the CuC1 microcrystallites. These predictions have been confirmed expriment ally4'5. Second, the two-dimensional excitons in quantum wells can superradiatively decay in the direction perpendicular to the surfaces2 . This brings about the quick response and the deviation of the excitons from ideal bosons at the same time. The latter effect as well as the two-dimensional macroscopic enhancement of the exction transition dipolemoment enhance the third-order optical susceptibility3. Both the superradiative decay rate and increase as does the coherent length, which is inversely proportional to the square root of the exciton line width6.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 1, 1990•7 citations

Quantum description of exciton-light coupled states for a thin film

Hiroshi Ajiki

The superposition coefficients of the coupled states of a photon and an exciton confined in a thin film are provided using Fano's method [U. Fano, Phys. Rev. 124, 1866 (1961)], in which the exciton interacts with continuum photon states. The coupled states are classified into leaky and surface modes, the latter of which are investigated with a focus on the dispersion relation, the exciton component, and their film-thickness dependence. The obtained coupled states enable us to study exciton-mediated optical properties that cannot be described by a semiclassical scheme, such as photoluminescence and the radiative decay of a biexciton. As applications of the coupled states, we calculate the population decay dynamics and photoluminescence spectra of an exciton in a thin film.

Physical Review B•Oct 29, 2015•1 citation
The theory of superradiance of excitons in thin crystal films is presented. While the broken crystal symmetry in the direction normal to the film plane renders the radiative decay of the exciton possible, the remaining crystal symmetry on the film leads to phase coherence between the exciton and the photon fields everywhere on the film. Consequently, a trading between the degrees of freedom of the radiation field and those of the atoms is shown to be responsible for the predicted superradiative enhancement of the exciton decay by a factor ( lambda /d) 2 >>1 in the optical region.
The radiative frequency shift of an exciton in a thin semiconductor film, like its radiative level width, is shown to be superradiatively enhanced. Unlike the latter, however, a finite frequency shift can only be obtained after proper renormalization for the correlated system. The shift is found to be inversely proportional to the square of the factor k0{\mathit{k}}_{0}k0​d and proportional to the film thickness T, k0{\mathit{k}}_{0}k0​=Eqn{\mathit{E}}_{\mathbf{q}\mathit{n}}Eqn​/\ensuremath{\Elzxh}c, Eqn{\mathit{E}}_{\mathbf{q}\mathit{n}}Eqn​ being the exciton energy gap and d the lattice constant of the semiconductor. Therefore, the coherent frequency shift can be observed experimentally if one varies the thickness, or the exciton energy gap Eqn{\mathit{E}}_{\mathbf{q}\mathit{n}}Eqn​ by imposing high pressure.
This thesis studies superradiance and subradiance in the normal modes of excitation of systems of resonant nuclei. The nuclei are treated as classical electric dipole oscillators interacting through their radiation fields. This coupling radically alters the radiative decay of the system relative to the decay of an isolated nucleus, and leads to both superradiant and subradiant states with strongly enhanced or suppressed radiative decay rates, and with normal mode frequencies which can be strongly shifted from the natural resonance frequency. This issue is of considerable current interest because it is now possible to create spatially coherent single exciton nuclear states by illuminating crystals containing resonant Mossbauer nuclei with synchrotron radiation pulses. The purpose of this thesis is to solve for the radiative eigenmodes in a system of nuclei and to investigate superradiance and subradiance both in the eigenmode solutions and in the synchrotron radiation produced nuclear exciton state.
Excitonic superradiance has been predicted to induce a rapid decay rate of coherently excited excitons in thin quantum wells and microspheres. In this paper we revisit this problem and derive the enhancement factor of the radiative decay due to superradiant effects. In a GaAs quantum well, the excitonic superradiant radiative decay can be roughly 320 times faster than the decay of a free electron-hole pair. The exciton decay rate depends strongly on the lateral size of the wave function when the size is smaller than the inverse of the wave vector of the emitted light. In a GaAs quantum well this corresponds to a distance of \ensuremath{\approxeq}365 \AA{}. Therefore, it is predicted that localization and elastic phonon scattering may lead to decay rates substantially smaller than that predicted for an ideal quantum well. It is also shown that if the quantum well is placed inside a microcavity, the decay rate can be enhanced even further since the cavity modifies the available density of radiation states in a way that matches the superradiant emission. It is predicted that in a matched dielectric cavity the decay rate can be enhanced by an additional factor of 100, but that inhomogeneous broadening may in practice limit the possible enhancement.
Rapid superradiant decay of coherently excited excitons in thin quantum wells (QWs) on a time scale of approximately 10 ps has been theoretically predicted by several groups [1], however, the experimental observation of this ultrafast radiative recombination is still the subject of controversial discussions. A recent theoretical paper [2] concludes, that this radiative decay rate should be strongly enhanced in multiple QW (MQW) Bragg structures due to radiative coupling of excitons excited in different wells via the exchange of transverse photons.
We want to make the best use of the mesoscopic or macroscopic transition dipolemornent of excitons by controling the size and dimension of the materials. First, the semiconductor microcrystallites embedded in insulators or glasses are shown to have the mesoscopic transition dipolemoment of excitons1 . As a result, the exciton in CuC1 microcrystallite with the radius 80 A superradiatively decays in 100 pico-second2. Futhermore, the exciton-exciton interaction and the decay and relaxation of the exciton work effectively in deviating the excitons in the microcrystallite from ideal bosons and this system shows the large third-order optical susceptibility"3 of an order of iO esu when we assume the 0.1% packing of the CuC1 microcrystallites. These predictions have been confirmed expriment ally4'5. Second, the two-dimensional excitons in quantum wells can superradiatively decay in the direction perpendicular to the surfaces2 . This brings about the quick response and the deviation of the excitons from ideal bosons at the same time. The latter effect as well as the two-dimensional macroscopic enhancement of the exction transition dipolemoment enhance the third-order optical susceptibility3. Both the superradiative decay rate and increase as does the coherent length, which is inversely proportional to the square root of the exciton line width6.
The superposition coefficients of the coupled states of a photon and an exciton confined in a thin film are provided using Fano's method [U. Fano, Phys. Rev. 124, 1866 (1961)], in which the exciton interacts with continuum photon states. The coupled states are classified into leaky and surface modes, the latter of which are investigated with a focus on the dispersion relation, the exciton component, and their film-thickness dependence. The obtained coupled states enable us to study exciton-mediated optical properties that cannot be described by a semiclassical scheme, such as photoluminescence and the radiative decay of a biexciton. As applications of the coupled states, we calculate the population decay dynamics and photoluminescence spectra of an exciton in a thin film.