244 research outputs found
Influence of Pure Dephasing on Emission Spectra from Single Photon Sources
We investigate the light-matter interaction of a quantum dot with the
electromagnetic field in a lossy microcavity and calculate emission spectra for
non-zero detuning and dephasing. It is found that dephasing shifts the
intensity of the emission peaks for non-zero detuning. We investigate the
characteristics of this intensity shifting effect and offer it as an
explanation for the non-vanishing emission peaks at the cavity frequency found
in recent experimental work.Comment: Published version, minor change
Comparison of EIT schemes in semiconductor quantum dot structures: Impact of many-body interactions
We investigate the impact of many-body interactions on group-velocity
slowdown achieved via electromagnetically induced transparency in quantum dots
using three different coupling-probe schemes (ladder, V, and Lambda,
respectively). We find that for all schemes many-body interactions have an
important impact on the slow light properties. In the case of the Lambda and V
schemes, the minimum required coupling power to achieve slow light is
significantly reduced by many-body interactions. V type schemes are found to be
generally preferable due to a favorable redistribution of carriers in energy
space
Dynamics and condensation of polaritons in an optical nanocavity coupled to two-dimensional materials
We present a comprehensive investigation of the light-matter interaction
dynamics in two-dimensional materials coupled with a spectrally isolated cavity
mode in the strong coupling regime. The interaction between light and matter
breaks the translational symmetry of excitons in the two-dimensional lattice
and results in the emergence of a localized polariton state. Employing a novel
approach involving transformation to exciton reaction coordinates, we derive a
Markovian master equation to describe the formation of a macroscopic population
in the localized polariton state. Our study shows that the construction of a
large-scale polariton population is affected by correction terms addressing the
breakdown of translational symmetry. Increasing the spatial width of the cavity
mode increases the Coulomb scattering rates while the correction terms saturate
and affect the system's dynamics progressively less. Tuning the lattice
temperature can induce bistability and hysteresis with different origins than
those recognized for quantum wells in larger microcavities. We identify a limit
temperature as a key factor for stimulated emissions and
forming a macroscopic population, enriching our understanding of strong
coupling dynamics in systems with extreme confinement.Comment: 15 pages, 15 figure
Microscopic theory of phonon-induced effects on semiconductor quantum dot decay dynamics in cavity QED
We investigate the influence of the electron-phonon interaction on the decay
dynamics of a quantum dot coupled to an optical microcavity. We show that the
electron-phonon interaction has important consequences on the dynamics,
especially when the quantum dot and cavity are tuned out of resonance, in which
case the phonons may add or remove energy leading to an effective non-resonant
coupling between quantum dot and cavity. The system is investigated using two
different theoretical approaches: (i) a second-order expansion in the bare
phonon coupling constant, and (ii) an expansion in a polaron-photon coupling
constant, arising from the polaron transformation which allows an accurate
description at high temperatures. In the low temperature regime we find
excellent agreement between the two approaches. An extensive study of the
quantum dot decay dynamics is performed, where important parameter dependencies
are covered. We find that in general the electron-phonon interaction gives rise
to a greatly increased bandwidth of the coupling between quantum dot and
cavity. At low temperature an asymmetry in the quantum dot decay rate is
observed, leading to a faster decay when the quantum dot has a larger energy
than to the cavity. We explain this as due to the absence of phonon absorption
processes. Furthermore, we derive approximate analytical expressions for the
quantum dot decay rate, applicable when the cavity can be adiabatically
eliminated. The expressions lead to a clear interpretation of the physics and
emphasizes the important role played by the effective phonon density,
describing the availability of phonons for scattering, in quantum dot decay
dynamics. Based on the analytical expressions we present the parameter regimes
where phonon effects are expected to be important. Also, we include all
technical developments in appendices.Comment: published PRB version, comments are very welcom
Non-markovian model of photon-assisted dephasing by electron-phonon interactions in a coupled quantum-dot-cavity system
We investigate the influence of electron-phonon interactions on the dynamical
properties of a quantum-dot-cavity QED system. We show that non-Markovian
effects in the phonon reservoir lead to strong changes in the dynamics, arising
from photon-assisted dephasing processes, not present in Markovian treatments.
A pronounced consequence is the emergence of a phonon induced spectral
asymmetry when detuning the cavity from the quantum-dot resonance. The
asymmetry can only be explained when considering the polaritonic quasi-particle
nature of the quantum-dot-cavity system. Furthermore, a temperature induced
reduction of the light-matter coupling strength is found to be relevant in
interpreting experimental data, especially in the strong coupling regime.Comment: 4 pages, 4 figures, published in Physical Review Letters, changes
according to referees comments, comments are welcom
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