19,810 research outputs found
Quantum deconvolution
We propose a method for stably removing noise from measurements of a quantum
many-body system. The question is cast to a linear inverse problem by using a
quantum Fischer information metric as figure of merit. This requires the
ability to compute the adjoint of the noise channel with respect to the metric,
which can be done analytically when the metric is evaluated at a Gaussian
(quasi-free) state. This approach can be applied effectively to n-point
functions of a quantum field theory. For translation invariant noise, this
yields a stable deconvolution method on the first moments of the field which
differs from what one would obtain from a purely classical analysis
Simple method for sub-diffraction resolution imaging of cellular structures on standard confocal microscopes by three-photon absorption of quantum dots
This study describes a simple technique that improves a recently developed 3D sub-diffraction imaging method based on three-photon absorption of commercially available quantum dots. The method combines imaging of biological samples via tri-exciton generation in quantum dots with deconvolution and spectral multiplexing, resulting in a novel approach for multi-color imaging of even thick biological samples at a 1.4 to 1.9-fold better spatial resolution. This approach is realized on a conventional confocal microscope equipped with standard continuous-wave lasers. We demonstrate the potential of multi-color tri-exciton imaging of quantum dots combined with deconvolution on viral vesicles in lentivirally transduced cells as well as intermediate filaments in three-dimensional clusters of mouse-derived neural stem cells (neurospheres) and dense microtubuli arrays in myotubes formed by stacks of differentiated C2C12 myoblasts
A measurement-based approach to quantum arrival times
For a quantum-mechanically spread-out particle we investigate a method for
determining its arrival time at a specific location. The procedure is based on
the emission of a first photon from a two-level system moving into a
laser-illuminated region. The resulting temporal distribution is explicitly
calculated for the one-dimensional case and compared with axiomatically
proposed expressions. As a main result we show that by means of a deconvolution
one obtains the well known quantum mechanical probability flux of the particle
at the location as a limiting distribution.Comment: 11 pages, 4 figures, submitted to Phys. Rev.
Coherent Processing of a Qubit Using One Squeezed State
We use a single squeezed state to represent a qubit, which can be coherently
processed in a deconvolution picture (DP) in the presence of noise. We avail
ourselves of the fact that when evolution is governed by a quadratic
dissipative equation, there exists a basis of squeezed states that evolves to
another basis of such states in the DP. An operator acts as an impurity filter,
restoring the coherence lost from the inexorable interactions of the qubit with
its surroundings.Comment: Published version includes one new section and some reorganizatio
Mammographic image restoration using maximum entropy deconvolution
An image restoration approach based on a Bayesian maximum entropy method
(MEM) has been applied to a radiological image deconvolution problem, that of
reduction of geometric blurring in magnification mammography. The aim of the
work is to demonstrate an improvement in image spatial resolution in realistic
noisy radiological images with no associated penalty in terms of reduction in
the signal-to-noise ratio perceived by the observer. Images of the TORMAM
mammographic image quality phantom were recorded using the standard
magnification settings of 1.8 magnification/fine focus and also at 1.8
magnification/broad focus and 3.0 magnification/fine focus; the latter two
arrangements would normally give rise to unacceptable geometric blurring.
Measured point-spread functions were used in conjunction with the MEM image
processing to de-blur these images. The results are presented as comparative
images of phantom test features and as observer scores for the raw and
processed images. Visualization of high resolution features and the total image
scores for the test phantom were improved by the application of the MEM
processing. It is argued that this successful demonstration of image
de-blurring in noisy radiological images offers the possibility of weakening
the link between focal spot size and geometric blurring in radiology, thus
opening up new approaches to system optimization.Comment: 18 pages, 10 figure
Calculated and measured Auger lineshapes in clean Si(100)2Ă1, SiOx and Si-NO
The measurements were performed on the clean 2*1 reconstructed Si(100) surface and this surface exposed to molecular oxygen (O2) or nitric oxide (NO) at room temperature. The data were corrected for electron loss and spectrometer distortions using the authors' newly developed deconvolution method. This method which uses global approximation and spline functions can overcome several difficulties with respect to deconvolution and allows them to derive high-quality auger lineshapes from the SiL2.3 VV Auger electron spectra. The authors experimentally obtained Auger lineshapes were compared with theoretical lineshapes utilising quantum chemical cluster calculations. They used this type of calculation for the interpretation of the Auger lineshape in the actual p-like and s-like partial local density of states for different types of silicon atom. The observed intensities of the major features are in reasonable agreement with the authors' calculations
- âŠ