71,661 research outputs found
Linewidth broadening of a quantum dot coupled to an off-resonant cavity
We study the coupling between a photonic crystal cavity and an off-resonant
quantum dot under resonant excitation of the cavity or the quantum dot.
Linewidths of the quantum dot and the cavity as a function of the excitation
laser power are measured. We show that the linewidth of the quantum dot,
measured by observing the cavity emission, is significantly broadened compared
to the theoretical estimate. This indicates additional incoherent coupling
between the quantum dot and the cavity.Comment: 5 pages, 4 figure
Optical Properties and Modal Gain of InGaN Quantum Dot Stacks
We present investigations of the optical properties of stacked InGaN quantum
dot layers and demonstrate their advantage over single quantum dot layer
structures. Measurements were performed on structures containing a single layer
with quantum dots or threefold stacked quantum dot layers, respectively. A
superlinear increase of the quantum dot related photoluminescence is detected
with increasing number of quantum dot layers while other relevant GaN related
spectral features are much less intensive when compared to the
photoluminescence of a single quantum dot layer. The quantum dot character of
the active material is verified by microphotoluminescence experiments at
different temperatures. For the possible integration within optical devices in
the future the threshold power density was investigated as well as the modal
gain by using the variable stripe length method.Comment: 9 Pages, 4 Figure
Influence of phonons on exciton-photon interaction and photon statistics of a quantum dot
In this paper, we investigate, phonon effects on the optical properties of a
spherical quantum dot. For this purpose, we consider the interaction of a
spherical quantum dot with classical and quantum fields while the exciton of
quantum dot interacts with a solid state reservoir. We show that phonons
strongly affect the Rabi oscillations and optical coherence on first
picoseconds of dynamics. We consider the quantum statistics of emitted photons
by quantum dot and we show that these photons are anti-bunched and obey the
sub-Poissonian statistics. In addition, we examine the effects of detuning and
interaction of quantum dot with the cavity mode on optical coherence of energy
levels. The effects of detuning and interaction of quantum dot with cavity mode
on optical coherence of energy levels are compared to the effects of its
interaction with classical pulse
A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots
We demonstrate a reconfigurable quantum dot gate architecture that
incorporates two interchangeable transport channels. One channel is used to
form quantum dots and the other is used for charge sensing. The quantum dot
transport channel can support either a single or a double quantum dot. We
demonstrate few-electron occupation in a single quantum dot and extract
charging energies as large as 6.6 meV. Magnetospectroscopy is used to measure
valley splittings in the range of 35-70 microeV. By energizing two additional
gates we form a few-electron double quantum dot and demonstrate tunable tunnel
coupling at the (1,0) to (0,1) interdot charge transition.Comment: Related papers at http://pettagroup.princeton.ed
Non-invasive detection of charge-rearrangement in a quantum dot in high magnetic fields
We demonstrate electron redistribution caused by magnetic field on a single
quantum dot measured by means of a quantum point contact as non-invasive
detector. Our device which is fabricated by local anodic oxidation allows to
control independently the quantum point contact and all tunnelling barriers of
the quantum dot. Thus we are able to measure both the change of the quantum dot
charge and also changes of the electron configuration at constant number of
electrons on the quantum dot. We use these features to exploit the quantum dot
in a high magnetic field where transport through the quantum dot displays the
effects of Landau shells and spin blockade. We confirm the internal
rearrangement of electrons as function of the magnetic field for a fixed number
of electrons on the quantum dot.Comment: 4 pages, 5 figure
Correlation-induced resonances and population switching in a quantum dot coulomb valley
Strong correlation effects on electron transport through a spinless quantum
dot are considered. When two single-particle levels in the quantum dot are
degenerate, a conserved pseudospin degree of freedom appears for general
tunneling matrix elements between the quantum dot and leads. Local fluctuations
of the pseudospin in the quantum dot give rise to a pair of asymmetric
conductance peaks near the center of a Coulomb valley. An exact relation to the
population switching is provided.Comment: Fig. 4 and some technical details removed. To appear in PR
Near-threshold properties of the electronic density of layered quantum-dots
We present a way to manipulate an electron trapped in a layered quantum dot
based on near-threshold properties of one-body potentials. We show that
potentials with a simple global parameter allows the manipulation of the wave
function changing its spatial extent. This phenomenon seems to be fairly
general and could be implemented using current quantum-dot quantum wells
technologies and materials if a proper layered quantum dot is designed. The
layered quantum dot under consideration is similar to a quantum-dot quantum
well device, i.e. consists of a spherical core surrounded by successive layers
of different materials. The number of layers and the constituent material are
chosen to highlight the near-threshold properties.
In particular we show that the near-threshold phenomena can be observed using
an effective mass approximation model that describes the layered quantum dot
which is consistent with actual experimental parameters.Comment: 15 pages, 6 figures, regular articl
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