The concepts of quantum detection and estimation theory can be of great help in the analysis of faint signals, which must be treated with extreme care due to the fragility and subtlety. But this is surely not the only domain, where the advanced concepts may be applied. Strong optical fields can be analyzed by similar techniques since by virtue of first quantization any optical wave plays role of a quantum state. More precisely, a classical mode of light can be given and alternative interpretation as a quantum state of the spatial degrees of freedom of a photon. Here the formulation of classical optics meets those of quantum information processing. The goal of the research is to optimize classical sensing schemes of strong signals in order to attain the best performance allowed by Nature. As examples of the approach, measurement of two point-like sources separation and full characterization of laser beams by a phase-space tomography will be discussed both theoretically and experimentally.
Wavefront sensing is an advanced technology that enables the precise determination of the phase of a light field, a
critical information for many applications, such as noncontact metrology, adaptive optics, and vision correction.
Here, we reinterpret the operation of wavefront sensors as a simultaneous unsharp measurement of position
and momentum. Utilizing quantum tomography techniques we report an experimental characterization and 3D
imaging of a multimode laser light.
Adaptive image fusion system based on neural network principle was realized. It works with digitalized video
sequences of visible and infrared band sensors, and is able to produce the optimal fused image for a wide range
of lighting conditions through an adaptive change of a fusion algorithm. The change is driven by a change in
the measured statistic of the input images. The best algorithm for a particular input is found with the help of
an objective measurement of the fusion process quality.
Maximum-likelihood estimation is an important method of inference.
Recently, maximum-likelihood techniques have been successfully
applied to absorption tomography of weakly as well as strongly
absorbing materials. In this presentation we generalize this
method to the phase contrast tomography, which combines the phase
estimation and tomography. Unlike the standard phase fitting
followed by the filtered back-projection, the developed procedure
gives reasonable results also when applied to very noisy data or
data consisting of only a few measured projections. The proposed
method could therefore considerably shorten measuring times in
applications involving low intensity beams, such as phase
tomography with low intense X-ray beams or neutrons.
We study teleportation of qubits with imperfect Bell analysis on the sender's side. For the chosen family of Alice's measurements we find Bob's operations maximizing the overall fidelity of the teleportation protocol. In certain cases the optimum maps turn out to be nonunitary operations. This means that decoherence can sometimes enhance the performance of quantum teleportation protocols.
An experimental comparison of several operational phase concepts is presented. In particular, it is shown that statistically motivated evaluation of experimental data may lead to a significant improvement in phase fitting upon the conventional Noh, Fourgeres and Mandel procedure. The analysis is extended to the asymptotic limit of large intensities, where a strong evidence in favor of multi- dimensional procedures has been found.