55 citations · 303 across the 18 of their papers we have counts for
18 papers
Transiently changing shape of the photon number distribution in a quantum-dot--cavity system driven by chirped laser pulses
M. Cosacchi, T. Seidelmann, F. Ungar +3
We have simulated the time evolution of the photon number distribution in a semiconductor quantum dot-microcavity system driven by chirped laser pulses and compare with unchirped r…
Spin dynamics of hot excitons in diluted magnetic semiconductors with spin-orbit interaction
Florian Ungar, Pablo Ignacio Tamborenea, Vollrath Martin Axt
We explore the impact of a Rashba-type spin-orbit interaction in the conduction band on the spin dynamics of hot excitons in diluted magnetic semiconductor quantum wells. In materi…
Role of excited states in the dynamics of excitons and their spins in diluted magnetic semiconductors
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
We theoretically investigate the impact of excited states on the dynamics of the exciton ground state in diluted magnetic semiconductor quantum wells. Exploiting the giant Zeeman s…
Emission-frequency separated high quality single-photon sources enabled by phonons
Michael Cosacchi, Florian Ungar, Moritz Cygorek +2
We demonstrate theoretically that the single-photon purity of photons emitted from a quantum dot exciton prepared by phonon-assisted off-resonant excitation can be significantly hi…
Phonon-induced enhancement of photon entanglement in quantum dot-cavity systems
Tim Seidelmann, Florian Ungar, Andreas M. Barth +4
We report on simulations of the degree of polarization entanglement of photon pairs simultaneously emitted from a quantum dot-cavity system that demand revisiting the role of phono…
Origins of overshoots in the exciton spin dynamics in semiconductors
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
We investigate the origin of overshoots in the exciton spin dynamics after resonant optical excitation. As a material system, we focus on diluted magnetic semiconductor quantum wel…
From strong to weak temperature dependence of the two-photon entanglement resulting from the biexciton cascade inside a cavity
Tim Seidelmann, Florian Ungar, Moritz Cygorek +4
We investigate the degree of entanglement quantified by the concurrence of photon pairs that are simultaneously emitted in the biexciton-exciton cascade from a quantum dot in a cav…
Phonon-induced quantum ratchet in the exciton spin dynamics in diluted magnetic semiconductors in a magnetic field
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
Magnetically doped semiconductors are well known for their giant Zeeman splittings which can reach several meV even in relatively small external magnetic fields. After preparing a…
Phonon impact on the dynamics of resonantly excited and hot excitons in diluted magnetic semiconductors
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
Phonons are well known to be the main mechanism for the coupling between bright and dark excitons in nonmagnetic semiconductors. Here, we investigate diluted magnetic semiconductor…
Many-body correlations brought to light in absorption spectra of diluted magnetic semiconductors
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
Diluted magnetic semiconductors are materials well known to exhibit strong correlations which typically manifest in carrier-mediated magnetic ordering. In this Rapid Communication,…
Path-integral approach for nonequilibrium multi-time correlation functions of open quantum systems coupled to Markovian and non-Markovian environments
Michael Cosacchi, Moritz Cygorek, Florian Ungar +3
Using a real-time path integral approach we develop an algorithm to calculate multi-time correlation functions of open few-level quantum systems that is applicable to highly nonequ…
Trend reversal in the magnetic-field dependence of exciton spin-transfer rates in diluted magnetic semiconductors due to non-Markovian dynamics
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
We investigate theoretically the influence of an external magnetic field on the spin dynamics of excitons in diluted magnetic semiconductor quantum wells. To this end, we apply a q…
Comparison of different concurrences characterizing photon-pairs generated in the biexciton cascade in quantum dots coupled to microcavities
Moritz Cygorek, Florian Ungar, Tim Seidelmann +4
We compare three different notions of concurrence to measure the polarization entanglement of two-photon states generated by the biexciton cascade in a quantum dot embedded in a mi…
Nonlinear cavity feeding and unconventional photon statistics in solid-state cavity QED revealed by many-level real-time path-integral calculations
Moritz Cygorek, Andreas M. Barth, Florian Ungar +2
The generation of photons in a microcavity coupled to a laser-driven quantum dot interacting with longitudinal acoustic (LA) phonons is studied in the regime of simultaneously stro…
Quantum kinetic equations for the ultrafast spin dynamics of excitons in diluted magnetic semiconductor quantum wells after optical excitation
Florian Ungar, Moritz Cygorek, Vollrath Martin Axt
Quantum kinetic equations of motion for the description of the exciton spin dynamics in II-VI diluted magnetic semiconductor quantum wells with laser driving are derived. The model…
Nonexponential spin decay in a quantum kinetic description of the D'yakonov-Perel' mechanism mediated by impurity scattering
Michael Cosacchi, Moritz Cygorek, Florian Ungar +1
The electron spin dynamics in an optically excited narrow quantum well is studied, where the electron spins precess in a k-dependent magnetic field while the electrons scatter at l…
Influence of non-magnetic impurity scattering on the spin dynamics in diluted magnetic semiconductors
Moritz Cygorek, Florian Ungar, Pablo Ignacio Tamborenea +1
The doping of semiconductors with magnetic impurities gives rise not only to a spin-spin interaction between quasi-free carriers and magnetic impurities, but also to a local spin-i…
Ultrafast spin dynamics in II-VI diluted magnetic semiconductors with spin-orbit interaction
Florian Ungar, Moritz Cygorek, Pablo I. Tamborenea +1
We study theoretically the ultrafast spin dynamics of II-VI diluted magnetic semiconductors in the presence of spin-orbit interaction. Our goal is to explore the interplay or compe…