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

Residual dephasing mechanism at low temperature in semiconductor quantum dots

Kazuhiro Takemoto, Michio Ikezawa, Yasuaki Masumoto

Published Jan 1, 2002• 0 citations
OpenAlex

Abstract

We have systematically investigated low-temperature excitonic dephasing in CuBr and CdSe quantum dots by means of heterodynedetected accumulated photon echo method. It has been clarified that two characteristic mechanisms determine the homogeneous broadening at low temperature: the small energy excitation in two-level system and the twophonon Raman process of confined acoustic phonons. The former brings about the matrix-dependent behaviour of the temperature dependence between CuBr quantum dots in glass and CuBr quantum dots in NaBr below 15 K. Confined acoustic-phonon contribution becomes dominant above 15 K and 10 K for CuBr and CdSe quantum dots, respectively. These results closely resemble the previous report of CuCl quantum dots in weak confinement regime, showing the universal role of surface-related effects and confined phonon scattering as the residual dephasing mechanism of semiconductor quantum dots in matrices at low temperature.

Related papers

Low‐temperature dephasing mechanism of very small quantum dots: the role of confined phonons and surrounding matrices

Kazuya Takemoto, Michio Ikezawa, Yasuaki Masumoto

Temperature dependence of the homogeneous linewidth of CuBr quantum dots in glass and NaBr matrices and CdSe quantum dots in glass matrix has been investigated using heterodyne-detected accumulated photon echo. We can reproduce the observed nonlinear temperature dependence considering two characteristic mechanisms: the small energy excitation in two-level system and the two-phonon Raman process of confined acoustic phonons. The interaction with the two-level system is dominant below 15 K and 10 K for CuBr and CdSe quantum dots, respectively. Above these temperatures the interaction with confined phonons is dominant. These results are similar to those of a previous study of CuCl quantum dots in glass, showing the universal influence of confined phonons and surrounding matrices on the low-temperature dephasing process of very small semiconductor quantum dots.

Physica status solidi. C, Conferences and critical reviews/Physica status solidi. C, Current topics in solid state physics•Jul 1, 2003•3 citations

Homogeneous Width of Confined Excitons in Quantum Dots at Very Low Temperatures

Yasuaki Masumoto, Michio Ikezawa, Byung‐Ryool Hyun +2 more

The temperature-dependent homogeneous width of confined excitons in CuCl, CuBr and CdSe quantum dots was investigated at very low temperatures down to 0.6 K by means of accumulated photon echo. The observed nonlinear temperature dependence of the homogeneous width at low temperatures is explained by the interaction with confined acoustic phonons for CdSe quantum dots or very small excitation in the two-level system for CuCl and CuBr quantum dots. At the lowest temperature, the homogeneous width of confined excitons in CuCl, CuBr and CdSe quantum dots becomes 1–2 μeV, 23–59 μeV and 0.16–0.25 meV, respectively. It depends on the surrounding matrix for CuCl quantum dots and the radius of dots for CuBr and CdSe quantum dots. These results suggest surroundings of quantum dots dominate the low temperature dephasing mechanism, i.e. homogeneous width of the optical spectra, of real quantum dots.

physica status solidi (b)•Apr 1, 2001•27 citations

Ultranarrow homogeneous broadening of confined excitons in quantum dots: Effect of the surrounding matrix

Michio Ikezawa, Yasuaki Masumoto

Ultranarrow homogeneous linewidth of a ${Z}_{3}$ exciton in CuCl quantum dots was studied by using accumulated photon echo. CuCl quantum dots embedded in two kinds of matrices, namely, an alminoborosilicate glass and a NaCl crystal, were studied. The narrowest homogeneous linewidth at low temperature was 1 $\ensuremath{\mu}\mathrm{eV}.$ The temperature dependence of the homogeneous linewidth was similar, above 5 K for both kinds of samples, but in the lower-temperature region, a remarkable difference was observed between them. It indicates that the matrix definitely affects the dephasing process of a confined exciton in quantum dots at low temperatures. The observed temperature dependence was explained by the contribution of the confined phonon in quantum dots and the two-level system in the matrix.

Physical review. B, Condensed matter•May 15, 2000•42 citations

Phonon Dephasing of the Exciton in InAs / GaAs Quantum Dots

Andrzej Janutka, Lucjan Jacak, J. Krasnyj +1 more

The interaction of a exciton confined in a semiconductor quantum dot (QD) with bulk phonons (acoustical and optical) responsible for the exciton dephasing is studied. The decoherence of the exciton due to the creation of a polaron with long-living or decaying phonons is described. Characteristic dephasing times for an InAs / GaAs QD are estimated using Green function methods in order to determine fundamental time limitations for use of the QD exciton in quantum information processing.

Open Systems & Information Dynamics•Dec 1, 2004•0 citations

Accumulated Photon Echo in CuBr Quantum Dots

Takashi Kuroda, F. Minami, Kuon Inoue +1 more

We have investigated nonlinear coherent transients of confined excitons in CuBr quantum dots with use of a three-pulse photon-echo technique. The echo signal shows quantum beats between LO-phonon coupled exciton levels, reflecting a strong electron–phonon interaction in the present quantum dots. The emission efficiency is found to be three orders of magnitude larger than those of ordinary semiconductors, implying that the significant accumulation effect is responsible for the nonlinear emission.

physica status solidi (a)•Nov 1, 1997•5 citations

Temperature dependence homogeneous broadening and gain recovery dynamics in InGaAs quantum dots

Paola Borri, W. Langbein, Stephan Schneider +4 more

We present temperature-dependent measurements of the dephasing time in the ground-state transition of strongly-confined InGaAs quantum dots, using a highly sensitive four-wave mixing technique. At low temperature we measure a dephasing time of several hundred picoseconds. Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian lineshape with a sharp zero-phonon line and a broad band from elastic exciton-acoustic phonon interactions. We also explore the dephasing time beyond the one exciton occupation, by electrically injecting carriers. Electrical injection into the barrier region results in a dominantly pure dephasing of the excitonic ground-state transition. Once the injected carriers have filled the electronic ground state, additional filling of the excited states creates multiexcitons that show a fast dephasing due to population relaxation.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Jun 5, 2002•0 citations
We have systematically investigated low-temperature excitonic dephasing in CuBr and CdSe quantum dots by means of heterodynedetected accumulated photon echo method. It has been clarified that two characteristic mechanisms determine the homogeneous broadening at low temperature: the small energy excitation in two-level system and the twophonon Raman process of confined acoustic phonons. The former brings about the matrix-dependent behaviour of the temperature dependence between CuBr quantum dots in glass and CuBr quantum dots in NaBr below 15 K. Confined acoustic-phonon contribution becomes dominant above 15 K and 10 K for CuBr and CdSe quantum dots, respectively. These results closely resemble the previous report of CuCl quantum dots in weak confinement regime, showing the universal role of surface-related effects and confined phonon scattering as the residual dephasing mechanism of semiconductor quantum dots in matrices at low temperature.
Temperature dependence of the homogeneous linewidth of CuBr quantum dots in glass and NaBr matrices and CdSe quantum dots in glass matrix has been investigated using heterodyne-detected accumulated photon echo. We can reproduce the observed nonlinear temperature dependence considering two characteristic mechanisms: the small energy excitation in two-level system and the two-phonon Raman process of confined acoustic phonons. The interaction with the two-level system is dominant below 15 K and 10 K for CuBr and CdSe quantum dots, respectively. Above these temperatures the interaction with confined phonons is dominant. These results are similar to those of a previous study of CuCl quantum dots in glass, showing the universal influence of confined phonons and surrounding matrices on the low-temperature dephasing process of very small semiconductor quantum dots.
The temperature-dependent homogeneous width of confined excitons in CuCl, CuBr and CdSe quantum dots was investigated at very low temperatures down to 0.6 K by means of accumulated photon echo. The observed nonlinear temperature dependence of the homogeneous width at low temperatures is explained by the interaction with confined acoustic phonons for CdSe quantum dots or very small excitation in the two-level system for CuCl and CuBr quantum dots. At the lowest temperature, the homogeneous width of confined excitons in CuCl, CuBr and CdSe quantum dots becomes 1–2 μeV, 23–59 μeV and 0.16–0.25 meV, respectively. It depends on the surrounding matrix for CuCl quantum dots and the radius of dots for CuBr and CdSe quantum dots. These results suggest surroundings of quantum dots dominate the low temperature dephasing mechanism, i.e. homogeneous width of the optical spectra, of real quantum dots.
Ultranarrow homogeneous linewidth of a Z3{Z}_{3}Z3​ exciton in CuCl quantum dots was studied by using accumulated photon echo. CuCl quantum dots embedded in two kinds of matrices, namely, an alminoborosilicate glass and a NaCl crystal, were studied. The narrowest homogeneous linewidth at low temperature was 1 $\ensuremath{\mu}\mathrm{eV}.$ The temperature dependence of the homogeneous linewidth was similar, above 5 K for both kinds of samples, but in the lower-temperature region, a remarkable difference was observed between them. It indicates that the matrix definitely affects the dephasing process of a confined exciton in quantum dots at low temperatures. The observed temperature dependence was explained by the contribution of the confined phonon in quantum dots and the two-level system in the matrix.
We have investigated nonlinear coherent transients of confined excitons in CuBr quantum dots with use of a three-pulse photon-echo technique. The echo signal shows quantum beats between LO-phonon coupled exciton levels, reflecting a strong electron–phonon interaction in the present quantum dots. The emission efficiency is found to be three orders of magnitude larger than those of ordinary semiconductors, implying that the significant accumulation effect is responsible for the nonlinear emission.
We present temperature-dependent measurements of the dephasing time in the ground-state transition of strongly-confined InGaAs quantum dots, using a highly sensitive four-wave mixing technique. At low temperature we measure a dephasing time of several hundred picoseconds. Between 7 and 100 K the polarization decay has two distinct components resulting in a non-Lorentzian lineshape with a sharp zero-phonon line and a broad band from elastic exciton-acoustic phonon interactions. We also explore the dephasing time beyond the one exciton occupation, by electrically injecting carriers. Electrical injection into the barrier region results in a dominantly pure dephasing of the excitonic ground-state transition. Once the injected carriers have filled the electronic ground state, additional filling of the excited states creates multiexcitons that show a fast dephasing due to population relaxation.