News archive

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Doris Reiter

New publication in 'New Journal of Physics' shows how phonons control the laser emission of quantum dot ensemble

archived: 11.10.2017
© Daniel Wigger

Semiconductor quantum dots can be used as active laser medium. Recently we have shown (News archive: 28.03.2017) that the laser output can be drastically enhanced by the interaction with phonons. Here, we now systematically study the phonon influence on the laser output accounting for different pulse forms and ensemble shapes. We thereby discriminate between two effects: the shaking and the adiabatic shift. Our work paves the way for a tailored laser control using phonons.


Read more in the publication. This work was done together with the group of Manfred Bayer from TU Dortmund, Germany.

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Doris Reiter

New publication in 'Physical Review B (Rapid)' about entering the reappearance regime

archived: 21.09.2017
© Doris Reiter

Optically excited carriers in semiconductor quantum dots interact with phonons. This interaction can hinder the optical state preparation. For large pulse intensities the phonon coupling becomes less efficient again and one enters the so called the reappearance regime. In collaboration with our experimental colleagues from Basel and samples from Bochum, we were able to demonstrate that it is possible to enter the reappearance regime.

Read more in the publication ...

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Doris Reiter

New publication in 'Physical Review B' about the phonon assisted preparation of dark excitons

archived: 31.08.2017
© Doris Reiter

Dark excitons in quantum dots can typically not be directly excited by a laser pulse. However, if a tilted magnetic field is applied, it becomes possible to optically excite the dark exciton. We show that the dark exciton preparation is not hindered by phonons. Furthermore we demonstrate that phonons widen the parameter range where an optical excitation of the dark exciton can take place.

Read more in the publication ...

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Doris Reiter

Richard Kerber is going for a research stay to London

archived: 05.07.2017
© Doris Reiter

Starting in May Richard Kerber will do research at the Department of Physics at Imperial College London within his PhD studies. To finance his stay he successfully applied for a fellowship of the German Academic Exchange Service (DAAD). In London, Richard will continue his research on the interaction of complex light fields with nano structures with a new focus on metamaterials. We wish Richard all the best for his stay in London!

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Doris Reiter

New publication in 'Physical Review B (Rapid)' about the optical generation of the biexciton using chirped pulses

archived: 27.06.2017
© Timo Kaldewey

Biexcitons in quantum dots can be used as source of entangled photons. For this, the biexciton should be created efficiently and with a large fidelity. We here show that by using an excitation with chirped laser pulses the biexciton can be created in a robust and resonant way, which is advantageous over previously used methods.

Read more in the publication ...

This work was done together with the group of Richard Warburton from Basel, Switzerland, and sampled from the group of Andreas Wieck from Bochum, Germany.

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Doris Reiter

New publication in 'Physical Review B' about a new method to describe quantum mechanics

archived: 10.05.2017
© D. Reiter

The carrier capture from a quantum wire in a quantum dot happens on ultrafast time and length scales and involves different dimensionalities. We have developed a Lindblad formalism to describe the dynamical capture process quantum mechanically. The computationally light formalisms give insights into the inhomogeneous dynamics at the nanoscale.

Read more in the publication ...

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Doris Reiter

New publication in 'Physical Review Letters' about the phonon controlled lasing

archived: 10.04.2017
© Doris Reiter

To make a laser one need a gain medium, which emits light into a resonator or cavity mode. Consider an ensemble of quantum dots with a certain energy distribution, most of them are out of resonance. Using a coherent phonon pulse, one can modify the quantum dot energies on a picosecond time scale. By this, the laser intensity can be enhanced or quenched. The intensity is further influenced by dynamical effects.

Read more in the publication ...

The work was performed together with the group of Manfred Bayer from the TU Dortmund, Germany, and samples from the University of Würzburg, Germany.

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Doris Reiter

New publication in 'ACS Photonics' about the interaction of twisted light with a nanostructure

archived: 28.03.2017
© Doris Reiter

A light pulse can be characterized by its polarization, denoting its spin angular momentum. In addition it can carry an orbital angular moment, which modifies the interaction with matter significantly. When a light beam carrying orbital angular momentum hits a plasmonic nanostructure, also modes which are usually dark can be excited. This makes it possible to read out information about the orbital angular momentum of the incident light.

Read more in the publication ...

This work was done together with the group of Ortwin Hess from Imperial College London, UK.

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Doris Reiter

New publication in 'Physical Review B' about the influence of phonons on the optical signals of a quantum dot

News 13032017
© Doris Reiter

When a quantum dot is excited by a continuous light field, the coupled quantum dot-light states are the new eigenstates of the system. The absorption spectra then consists of up to three lines, forming the so called Mollow triplet. By simulating a pump-probe set-up we analyse the dynamics of the quantum dot-light system. Further, we study the influence of phonons on the optical signals reflecting the relaxation into the ground state in the coupled system.

Read more in the paper ...