444 research outputs found
Storage capabilities of a 4-junction single electron trap with an on-chip resistor
We report on the operation of a single electron trap comprising a chain of
four Al/AlOx/Al tunnel junctions attached, at one side, to a memory island and,
at the other side, to a miniature on-chip Cr resistor R=50 kOhm which served to
suppress cotunneling. At appropriate voltage bias the bi-stable states of the
trap, with the charges differing by the elementary charge e, were realized. At
low temperature, spontaneous switching between these states was found to be
infrequent. For instance, at T=70 mK the system was capable of holding an
electron for more than 2 hours, this time being limited by the time of the
measurement.Comment: 3 pages of text and 2 figure
Metallic single-electron transistor without traditional tunnel barriers
We report on a new type of single-electron transistor (SET) comprising two
highly resistive Cr thin-film strips (~ 1um long) connecting a 1 um-long Al
island to two Al outer electrodes. These resistors replace small-area oxide
tunnel junctions of traditional SETs. Our transistor with a total asymptotic
resistance of 110 kOhm showed a very sharp Coulomb blockade and reproducible,
deep and strictly e-periodic gate modulation in wide ranges of bias currents I
and gate voltages V_g. In the Coulomb blockade region (|V| < 0.5 mV), we
observed a strong suppression of the cotunneling current allowing appreciable
modulation curves V-V_g to be measured at currents I as low as 100 fA. The
noise figure of our SET was found to be similar to that of typical Al/AlOx/Al
single-electron transistors.Comment: 5 pages incl. 4 fig
Conductance fluctuations in metallic nanogaps made by electromigration
We report on low temperature conductance measurements of gold nanogaps
fabricated by controlled electromigration. Fluctuations of the conductance due
to quantum interferences and depending both on bias voltage and magnetic field
are observed. By analyzing the voltage and magnetoconductance correlation
functions we determine the type of electron trajectories generating the
observed quantum interferences and the effective characteristic time of phase
coherence in our device.Comment: 5 pages, 4 figures, to appear in J. Appl. Phy
Domain-adversarial neural networks to address the appearance variability of histopathology images
Preparing and scanning histopathology slides consists of several steps, each
with a multitude of parameters. The parameters can vary between pathology labs
and within the same lab over time, resulting in significant variability of the
tissue appearance that hampers the generalization of automatic image analysis
methods. Typically, this is addressed with ad-hoc approaches such as staining
normalization that aim to reduce the appearance variability. In this paper, we
propose a systematic solution based on domain-adversarial neural networks. We
hypothesize that removing the domain information from the model representation
leads to better generalization. We tested our hypothesis for the problem of
mitosis detection in breast cancer histopathology images and made a comparative
analysis with two other approaches. We show that combining color augmentation
with domain-adversarial training is a better alternative than standard
approaches to improve the generalization of deep learning methods.Comment: MICCAI 2017 Workshop on Deep Learning in Medical Image Analysi
Inferring a Third Spatial Dimension from 2D Histological Images
Histological images are obtained by transmitting light through a tissue
specimen that has been stained in order to produce contrast. This process
results in 2D images of the specimen that has a three-dimensional structure. In
this paper, we propose a method to infer how the stains are distributed in the
direction perpendicular to the surface of the slide for a given 2D image in
order to obtain a 3D representation of the tissue. This inference is achieved
by decomposition of the staining concentration maps under constraints that
ensure realistic decomposition and reconstruction of the original 2D images.
Our study shows that it is possible to generate realistic 3D images making this
method a potential tool for data augmentation when training deep learning
models.Comment: IEEE International Symposium on Biomedical Imaging (ISBI), 201
Analysis and Optimization of a Piezoelectric Harvester on a Car Damper
AbstractLow power levels obtained from piezoelectric conversion of ambient vibrations appear to be a promising solution to supply wireless sensors embedded inside automotive suspension. However such a solution requires overall an optimum power extraction from the piezoelectric power harvester. This leads to the use of a sufficiently accurate and flexible modelling method to find the optimal characterics and configuration of the harvester. To this end, an innovative bond graph model of the piezoelectric harvester embedded in the quarter vehicle system is proposed for providing the harvested power when a car travels a road with a speed bump at 30km/h. Results show that around of 0.5 milliwatt electrical power is harvested when varying key parameters like the location and characteristics of the piezoelectric device
Enhanced transmission of slit arrays in an extremely thin metallic film
Horizontal resonances of slit arrays are studied. They can lead to an
enhanced transmission that cannot be explained using the single-mode
approximation. A new type of cavity resonance is found when the slits are
narrow for a wavelength very close to the period. It can be excited for very
low thicknesses. Optimization shows these structures could constitute
interesting monochromatic filters
Smearing of Coulomb Blockade by Resonant Tunneling
We study the Coulomb blockade in a grain coupled to a lead via a resonant
impurity level. We show that the strong energy dependence of the transmission
coefficient through the impurity level can have a dramatic effect on the
quantization of the grain charge. In particular, if the resonance is
sufficiently narrow, the Coulomb staircase shows very sharp steps even if the
transmission through the impurity at the Fermi energy is perfect. This is in
contrast to the naive expectation that perfect transmission should completely
smear charging effects.Comment: 4 pages, 3 figure
Quantum Manipulations of Small Josephson Junctions
Low-capacitance Josephson junction arrays in the parameter range where single
charges can be controlled are suggested as possible physical realizations of
the elements which have been considered in the context of quantum computers. We
discuss single and multiple quantum bit systems. The systems are controlled by
applied gate voltages, which also allow the necessary manipulation of the
quantum states. We estimate that the phase coherence time is sufficiently long
for experimental demonstration of the principles of quantum computation.Comment: RevTex, 15 pages,4 postscript figures, uuencoded, submitted to Phys.
Rev. Lett., estimates of the experimental parameters correcte
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