897 research outputs found
Square-rich fixed point polynomial evaluation on FPGAs
Polynomial evaluation is important across a wide range of application domains, so significant work has been done on accelerating its computation. The conventional algorithm, referred to as Horner's rule, involves the least number of steps but can lead to increased latency due to serial computation. Parallel evaluation algorithms such as Estrin's method have shorter latency than Horner's rule, but achieve this at the expense of large hardware overhead. This paper presents an efficient polynomial evaluation algorithm, which reforms the evaluation process to include an increased number of squaring steps. By using a squarer design that is more efficient than general multiplication, this can result in polynomial evaluation with a 57.9% latency reduction over Horner's rule and 14.6% over Estrin's method, while consuming less area than Horner's rule, when implemented on a Xilinx Virtex 6 FPGA. When applied in fixed point function evaluation, where precision requirements limit the rounding of operands, it still achieves a 52.4% performance gain compared to Horner's rule with only a 4% area overhead in evaluating 5th degree polynomials
Magnetic field and temperature sensing with atomic-scale spin defects in silicon carbide
Quantum systems can provide outstanding performance in various sensing
applications, ranging from bioscience to nanotechnology. Atomic-scale defects
in silicon carbide are very attractive in this respect because of the
technological advantages of this material and favorable optical and radio
frequency spectral ranges to control these defects. We identified several,
separately addressable spin-3/2 centers in the same silicon carbide crystal,
which are immune to nonaxial strain fluctuations. Some of them are
characterized by nearly temperature independent axial crystal fields, making
these centers very attractive for vector magnetometry. Contrarily, the
zero-field splitting of another center exhibits a giant thermal shift of -1.1
MHz/K at room temperature, which can be used for thermometry applications. We
also discuss a synchronized composite clock exploiting spin centers with
different thermal response.Comment: 8 pages, 7 figure
Simultaneous measurement of quality factor and wavelength shift by phase shift microcavity ring down spectroscopy
Optical resonant microcavities with ultra high quality factors are widely
used for biosensing. Until now, the primary method of detection has been based
upon tracking the resonant wavelength shift as a function of biodetection
events. One of the sources of noise in all resonant-wavelength shift
measurements is the noise due to intensity fluctuations of the laser source. An
alternative approach is to track the change in the quality factor of the
optical cavity by using phase shift cavity ring down spectroscopy, a technique
which is insensitive to the intensity fluctuations of the laser source. Here,
using biotinylated microtoroid resonant cavities, we show simultaneous
measurement of the quality factor and the wavelength shift by using phase shift
cavity ring down spectroscopy. These measurements were performed for
disassociation phase of biotin-streptavidin reaction. We found that the
disassociation curves are in good agreement with the previously published
results. Hence, we demonstrate not only the application of phase shift cavity
ring down spectroscopy to microcavities in the liquid phase but also
simultaneous measurement of the quality factor and the wavelength shift for the
microcavity biosensors in the application of kinetics measurements
Mode Bifurcation and Fold Points of Complex Dispersion Curves for the Metamaterial Goubau Line
In this paper the complex dispersion curves of the four lowest-order
transverse magnetic modes of a dielectric Goubau line () are
compared with those of a dispersive metamaterial Goubau line. The vastly
different dispersion curve structure for the metamaterial Goubau line is
characterized by unusual features such as mode bifurcation, complex fold
points, both proper and improper complex modes, and merging of complex and real
modes
Room-temperature near-infrared silicon carbide nanocrystalline emitters based on optically aligned spin defects
Bulk silicon carbide (SiC) is a very promising material system for
bio-applications and quantum sensing. However, its optical activity lies beyond
the near infrared spectral window for in-vivo imaging and fiber communications
due to a large forbidden energy gap. Here, we report the fabrication of SiC
nanocrystals and isolation of different nanocrystal fractions ranged from 600
nm down to 60 nm in size. The structural analysis reveals further fragmentation
of the smallest nanocrystals into ca. 10-nm-size clusters of high crystalline
quality, separated by amorphization areas. We use neutron irradiation to create
silicon vacancies, demonstrating near infrared photoluminescence. Finally, we
detect, for the first time, room-temperature spin resonances of these silicon
vacancies hosted in SiC nanocrystals. This opens intriguing perspectives to use
them not only as in-vivo luminescent markers, but also as magnetic field and
temperature sensors, allowing for monitoring various physical, chemical and
biological processes.Comment: 5 pages, 4 figure
All-optical dc nanotesla magnetometry using silicon vacancy fine structure in isotopically purified silicon carbide
We uncover the fine structure of a silicon vacancy in isotopically purified
silicon carbide (4H-SiC) and find extra terms in the spin Hamiltonian,
originated from the trigonal pyramidal symmetry of this spin-3/2 color center.
These terms give rise to additional spin transitions, which are otherwise
forbidden, and lead to a level anticrossing in an external magnetic field. We
observe a sharp variation of the photoluminescence intensity in the vicinity of
this level anticrossing, which can be used for a purely all-optical sensing of
the magnetic field. We achieve dc magnetic field sensitivity of 87 nT
Hz within a volume of mm at room temperature
and demonstrate that this contactless method is robust at high temperatures up
to at least 500 K. As our approach does not require application of
radiofrequency fields, it is scalable to much larger volumes. For an optimized
light-trapping waveguide of 3 mm the projection noise limit is below 100
fT Hz.Comment: 12 pages, 6 figures; additional experimental data and an extended
theoretical analysis are added in the second versio
- …