293 research outputs found
Design and evaluation of in-line product repair strategies for defect reduction in the production of electric drives
Manufacturing companies are continuously facing the challenge of operating their manufacturing processes and systems in order to deliver the required production rates of high quality products of increasing complexity, with limited use and waste of resources. This aspect is particularly critical in emerging sectors, such as the e-mobility industry, where state of the art quality and process control technologies show strong limitations. This paper proposes new solutions for implementing in-line product repair strategies in the production of electric drives for the automotive industry. Moreover, it develops an innovative quantitative tool to estimate the impact of the proposed strategies on the overall process-chain performance. The benefits of the approach are validated within a real industrial context
Subnanosecond spectral diffusion of a single quantum dot in a nanowire
We have studied spectral diffusion of the photoluminescence of a single CdSe
quantum dot inserted in a ZnSe nanowire. We have measured the characteristic
diffusion time as a function of pumping power and temperature using a recently
developed technique [G. Sallen et al, Nature Photon. \textbf{4}, 696 (2010)]
that offers subnanosecond resolution. These data are consistent with a model
where only a \emph{single} carrier wanders around in traps located in the
vicinity of the quantum dot
Single-photon excitation of a coherent state: catching the elementary step of stimulated light emission
When a single quantum of electromagnetic field excitation is added to the
same spatio-temporal mode of a coherent state, a new field state is generated
that exhibits intermediate properties between those of the two parents. Such a
single-photon-added coherent state is obtained by the action of the photon
creation operator on a coherent state and can thus be regarded as the result of
the most elementary excitation process of a classical light field. Here we
present and describe in depth the experimental realization of such states and
their complete analysis by means of a novel ultrafast, time-domain, quantum
homodyne tomography technique clearly revealing their non-classical character.Comment: 9 pages, 9 figures. Accepted for publication in Phys. Rev.
Tunable control of the bandwidth and frequency correlations of entangled photons
We demonstrate experimentally a new technique to control the bandwidth and
the type of frequency correlations (correlation, anticorrelation, and even
uncorrelation) of entangled photons generated by spontaneous parametric
downconversion. The method is based on the control of the group velocities of
the interacting waves. This technique can be applied in any nonlinear medium
and frequency band of interest. It is also demonstrated that this technique
helps enhance the quality of polarization entanglement even when femtosecond
pulses are used as a pump.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let
Efficient single-photon emission from electrically driven InP quantum dots epitaxially grown on Si(001)
The heteroepitaxy of III-V semiconductors on silicon is a promising approach
for making silicon a photonic platform for on-chip optical interconnects and
quantum optical applications. Monolithic integration of both material systems
is a long-time challenge, since different material properties lead to high
defect densities in the epitaxial layers. In recent years, nanostructures
however have shown to be suitable for successfully realising light emitters on
silicon, taking advantage of their geometry. Facet edges and sidewalls can
minimise or eliminate the formation of dislocations, and due to the reduced
contact area, nanostructures are little affected by dislocation networks. Here
we demonstrate the potential of indium phosphide quantum dots as efficient
light emitters on CMOS-compatible silicon substrates, with luminescence
characteristics comparable to mature devices realised on III-V substrates. For
the first time, electrically driven single-photon emission on silicon is
presented, meeting the wavelength range of silicon avalanche photo diodes'
highest detection efficiency
Subnanosecond spectral diffusion measurement using photon correlation
Spectral diffusion is a result of random spectral jumps of a narrow line as a
result of a fluctuating environment. It is an important issue in spectroscopy,
because the observed spectral broadening prevents access to the intrinsic line
properties. However, its characteristic parameters provide local information on
the environment of a light emitter embedded in a solid matrix, or moving within
a fluid, leading to numerous applications in physics and biology. We present a
new experimental technique for measuring spectral diffusion based on photon
correlations within a spectral line. Autocorrelation on half of the line and
cross-correlation between the two halves give a quantitative value of the
spectral diffusion time, with a resolution only limited by the correlation
set-up. We have measured spectral diffusion of the photoluminescence of a
single light emitter with a time resolution of 90 ps, exceeding by four orders
of magnitude the best resolution reported to date
Publisher’s Note: “Polymer-specific effects of bulk relaxation and stringlike correlated motion in the dynamics of a supercooled polymer melt” [J. Chem. Phys. 119, 5290 (2003)]
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70462/2/JCPSA6-120-14-6798-1.pd
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