© 2026 Aqora Quantum S.A.S.

Terms Privacy Legal Notice

Physical Review B

Exciton spin manipulation in In As ∕ Ga As quantum dots: Exchange interaction and magnetic field effects

Mathieu Sénès, Bernhard Urbaszek, X. Marie, Th. Amand, Jérôme Tribollet, F. Bernardot, C. Testelin, M. Chamarro, Jean‐Michel Gérard

Published Mar 31, 2005• 42 citations

Abstract

We report quantum beat phenomena between different polarization states in InAs quantum dots, observed in time-resolved photoluminescence and transient dichroism measurements. The polarization of the emitted light can be changed from linear to circular by applying a small magnetic field. Following quasiresonant excitation the electron and hole spin states remain stable during the exciton lifetime, independent of the applied magnetic field. We show that the exciton spin coherence is partially preserved in the energy relaxation process. These experiments enable us to measure the anisotropic exchange energy $\ensuremath{\Delta}{E}_{XY}$ and the exciton $g$ factor. We find $\ensuremath{\Delta}{E}_{XY}\ensuremath{\simeq}30\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{eV}$ and $g\ensuremath{\simeq}2.5$ for the quantum dot excitons.

DOI: 10.1103/physrevb.71.115334

Related papers

Optical alignment and polarization conversion of the neutral-exciton spin in individual InAs∕GaAs quantum dots

K. Kowalik, O. Krebs, Aristide Lemaître +2 more

We investigate exciton spin memory in individual $\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{As}$ self-assembled quantum dots via optical alignment and conversion of exciton polarization in a magnetic field. Quasiresonant phonon-assisted excitation is successfully employed to define the initial spin polarization of neutral excitons. The conservation of the linear polarization generated along the bright exciton eigenaxes of up to 90% and the conversion from circular to linear polarization of up to 47% both demonstrate a very long spin relaxation time with respect to the radiative lifetime. Results are quantitatively compared to a model of pseudospin $1∕2$ including heavy-to-light hole mixing.

arXiv:0801.0571•Physical Review B•Apr 28, 2008•37 citations

Coherent exciton spin dynamics and three-dimensional quantum state tomography in a single InAlAs quantum dot

J. Njala, Y. Yamamoto, Reina Kaji +2 more

We investigate the coherent exciton spin dynamics in a single InAlAs/AlGaAs quantum dot using time-resolved quantum state tomography. Under two-LO-phonon quasi-resonant excitation of neutral exciton, we observe pronounced quantum beats in the circular and diagonal polarization components, reflecting the fine-structure splitting ($Δ\approx 19.6 \ μ\text{eV}$). By employing a global fitting procedure across three orthogonal polarization bases, we demonstrate that the spin evolution is consistently described by a unified Hamiltonian dominated by the anisotropic exchange interaction. While the initial degree of circular polarization is limited to $\approx 0.28$ due to fast relaxation processes during carrier cooling, the subsequent dynamics reveal a long-lived spin coherence ($1.1 \pm 0.2$ ns) that exceeds the exciton lifetime ($\sim 767$ ps). Our analysis reveals that the spin-formation time is significantly shorter than the instrument response function, and the absence of a discernible Overhauser shift confirms a negligible influence from the local nuclear environment under the present conditions. These results provide a quantitative benchmark for the three-dimensional reconstruction of spin trajectories using differential polarization signals, demonstrating the feasibility of using quasi-resonant excitation for stable spin initialization in semiconductor nanostructures.

arXiv:2605.01801•May 3, 2026•0 citations

Transient Linear Birefringence in GaAs Quantum Wells: Magnetic Field Dependence of Coherent Exciton Spin Dynamics

R.E. Worsley, Nicholas Traynor, Treena Grevatt +1 more

We use reflective probing of transient linear birefringence to study coherent exciton dynamics in GaAs quantum wells as a function of applied magnetic field at low temperatures. The results show the significance of exchange-enhanced exciton spin relaxation for dephasing at zero field. In applied field the signals show background-free quantum beating which gives the exciton g factor and field-dependent dephasing time. The latter is dominated by spin relaxation which shows for the first time the dramatic slowdown predicted in earlier work.

Physical Review Letters•Apr 22, 1996•55 citations

Transient spectral hole burning spectroscopy of exciton spin flip processes in In(Ga)As quantum dots

Thomas G. Muller, G. Strasser, K. Unterrainer

Transient spectral hole burning measurements are performed on InAs/GaAs self-assembled quantum dots. In the case of cross-polarized pump and probe pulses, a spectral "antihole" emerges due to relaxation of the exciton spin.

IEEE Lasers and Electro-Optics Society Annual Meeting (LEOS)•Jan 1, 2005•0 citations

Exciton spin relaxation in InAs/InGaAlAs/InP(001) quantum dashes emitting near 1.55μm

M. Syperek, Łukasz Dusanowski, Michał Gawełczyk +5 more

Exciton spin and related optical polarization in self-assembled InAs/In0.53Ga0.23Al0.24As/InP(001) quantum dashes emitting at 1.55 μm are investigated by means of polarization- and time-resolved photoluminescence, as well as photoluminescence excitation spectroscopy, at cryogenic temperature. We investigate the influence of highly non-resonant and quasi-resonant optical spin pumping conditions on spin polarization and spin memory of the quantum dash ground state. We show that a spin pumping scheme, utilizing the longitudinal-optical-phonon-mediated coherent scattering process, can lead to the polarization degree above 50%. We discuss the role of intrinsic asymmetries in the quantum dash that influence values of the degree of polarization and its time evolution.

arXiv:1807.09143•Applied Physics Letters•Nov 7, 2016•11 citations

Observation of Dressed Excitonic States in a Single Quantum Dot

Gregor Jundt, Lucio Robledo, Alexander Högele +2 more

We report the observation of dressed states of a quantum dot. The optically excited exciton and biexciton states of the quantum dot are coupled by a strong laser field and the resulting spectral signatures are measured using differential transmission of a probe field. We demonstrate that the anisotropic electron-hole exchange interaction induced splitting between the x- and y-polarized excitonic states can be completely erased by using the ac-Stark effect induced by the coupling field, without causing any appreciable broadening of the spectral lines. We also show that by varying the polarization and strength of a resonant coupling field, we can effectively change the polarization axis of the quantum dot.

arXiv:0711.4205•Physical Review Letters•Apr 29, 2008•95 citations

We report quantum beat phenomena between different polarization states in InAs quantum dots, observed in time-resolved photoluminescence and transient dichroism measurements. The polarization of the emitted light can be changed from linear to circular by applying a small magnetic field. Following quasiresonant excitation the electron and hole spin states remain stable during the exciton lifetime, independent of the applied magnetic field. We show that the exciton spin coherence is partially preserved in the energy relaxation process. These experiments enable us to measure the anisotropic exchange energy

\ensuremath{\Delta}{E}_{XY}

and the exciton

g

factor. We find

\ensuremath{\Delta}{E}_{XY}\ensuremath{\simeq}30\phantom{\rule{0.3em}{0ex}}\ensuremath{\mu}\mathrm{eV}

and

g\ensuremath{\simeq}2.5

for the quantum dot excitons.

We investigate exciton spin memory in individual

\mathrm{In}\mathrm{As}∕\mathrm{Ga}\mathrm{As}

self-assembled quantum dots via optical alignment and conversion of exciton polarization in a magnetic field. Quasiresonant phonon-assisted excitation is successfully employed to define the initial spin polarization of neutral excitons. The conservation of the linear polarization generated along the bright exciton eigenaxes of up to 90% and the conversion from circular to linear polarization of up to 47% both demonstrate a very long spin relaxation time with respect to the radiative lifetime. Results are quantitatively compared to a model of pseudospin

1∕2

including heavy-to-light hole mixing.

We investigate the coherent exciton spin dynamics in a single InAlAs/AlGaAs quantum dot using time-resolved quantum state tomography. Under two-LO-phonon quasi-resonant excitation of neutral exciton, we observe pronounced quantum beats in the circular and diagonal polarization components, reflecting the fine-structure splitting (

Δ\approx 19.6 \ μ\text{eV}

). By employing a global fitting procedure across three orthogonal polarization bases, we demonstrate that the spin evolution is consistently described by a unified Hamiltonian dominated by the anisotropic exchange interaction. While the initial degree of circular polarization is limited to

\approx 0.28

due to fast relaxation processes during carrier cooling, the subsequent dynamics reveal a long-lived spin coherence (

1.1 \pm 0.2

ns) that exceeds the exciton lifetime (

\sim 767

ps). Our analysis reveals that the spin-formation time is significantly shorter than the instrument response function, and the absence of a discernible Overhauser shift confirms a negligible influence from the local nuclear environment under the present conditions. These results provide a quantitative benchmark for the three-dimensional reconstruction of spin trajectories using differential polarization signals, demonstrating the feasibility of using quasi-resonant excitation for stable spin initialization in semiconductor nanostructures.

We use reflective probing of transient linear birefringence to study coherent exciton dynamics in GaAs quantum wells as a function of applied magnetic field at low temperatures. The results show the significance of exchange-enhanced exciton spin relaxation for dephasing at zero field. In applied field the signals show background-free quantum beating which gives the exciton g factor and field-dependent dephasing time. The latter is dominated by spin relaxation which shows for the first time the dramatic slowdown predicted in earlier work.

Exciton spin and related optical polarization in self-assembled InAs/In0.53Ga0.23Al0.24As/InP(001) quantum dashes emitting at 1.55 μm are investigated by means of polarization- and time-resolved photoluminescence, as well as photoluminescence excitation spectroscopy, at cryogenic temperature. We investigate the influence of highly non-resonant and quasi-resonant optical spin pumping conditions on spin polarization and spin memory of the quantum dash ground state. We show that a spin pumping scheme, utilizing the longitudinal-optical-phonon-mediated coherent scattering process, can lead to the polarization degree above 50%. We discuss the role of intrinsic asymmetries in the quantum dash that influence values of the degree of polarization and its time evolution.

We report the observation of dressed states of a quantum dot. The optically excited exciton and biexciton states of the quantum dot are coupled by a strong laser field and the resulting spectral signatures are measured using differential transmission of a probe field. We demonstrate that the anisotropic electron-hole exchange interaction induced splitting between the x- and y-polarized excitonic states can be completely erased by using the ac-Stark effect induced by the coupling field, without causing any appreciable broadening of the spectral lines. We also show that by varying the polarization and strength of a resonant coupling field, we can effectively change the polarization axis of the quantum dot.