3,290 research outputs found
Photon splitting in atomic fields
Photon splitting due to vacuum polarization in the electric field of an atom
is considered. We survey different theoretical approaches to the description of
this nonlinear QED process and several attempts of its experimental
observation. We present the results of the lowest-order perturbation theory as
well as those obtained within the quasiclassical approximation being exact in
the external field strength. The experiment where photon splitting was really
observed for the first time is discussed in details. The results of this
experiment are compared with recent theoretical estimations.Comment: 45 pages, 24 figure
Qutrit state engineering with biphotons
The novel experimental realization of three-level optical quantum systems is
presented. We use the polarization state of biphotons to generate a specific
sequence of states that are used in the extended version of BB84 protocol. We
experimentally verify the orthogonality of the basis states and demonstrate the
ability to easily switch between them. The tomography procedure is employed to
reconstruct the density matrices of generated states.Comment: 5 pages, 4 figures. typos correcte
Polarization ququarts
We discuss the concept of polarization states of four-dimensional quantum
systems based on frequency non-degenerate biphoton field. Several quantum
tomography protocols were developed and implemented for measurement of an
arbitrary state of ququart. A simple method that does not rely on
interferometric technique is used to generate and measure the sequence of
states that can be used for quantum communication purposes.Comment: 13 pages, 10 figure
Experimental investigation of high-energy photon splitting in atomic fields
The new data analysis of the experiment, where the photon splitting in the
atomic fields has been observed for the first time, is presented. This
experiment was performed at the tagged photon beam of the ROKK-1M facility at
the VEPP-4M collider. In the energy region of 120-450 MeV, the statistics of
photons incident on the BGO target was collected. About 400
candidates to the photon splitting events were reconstructed. Within the
attained experimental accuracy, the experimental results are consistent with
the cross section calculated exactly in an atomic field. The predictions
obtained in the Born approximation significantly differ from the experimental
results.Comment: 11 pages, 6 figures, LaTe
East Turn of Russia: Problems and Prospects
In the article, the prospect of turn of Russia to the East - change of policy and economic guidelines and partners is considered, the Russian vision of “an Asian course” is described. Authors prove that emergence of the external economic strategy in East Asia will be for Russia the movement in a right direction - growth of this region is capable to be the driver for the Russian economy. It is described, how important is establishment of the direct channel of interaction between institutes of the Eurasian Economic Union and the European Union
Public-private partnership as an investment and innovation tool for medical facilities: a case of Ukrainian healthcare
This paper summarizes the scientific discussion on the issue of public-private partnership in healthcare sector. The main purpose of research is to analyze the public-private
partnership as the progressive form of innovative and investment mechanism in Ukrainian healthcare sector, taking into the consideration international experience in this sphere.
The key methods used in the conducted research are data analysis, summarization and comparison. The data synthesis and analysis are the basic value-added elements of this
research, which could help to find out the main prospective of PPP-model use in Ukrainian healthcare sector. The object of research is the group of countries such as USA, UK,
Canada, and BRIC countries, because namely they are the most progressive in public-private partnership in health care. Practical importance of the scientific research results
lies in defining the general principles of public-private partnerships and a set of criterion for its efficiency estimation. Also, the worldwide experience was analyzed in this
research and main challenges for its implementation in Ukrainian healthcare practice were considered. It is important for the further development of the healthcare sphere, and
improvement of the healthcare facilities’ activity in Ukraine. Further research directions are aimed at study of the specific issue of public-private partnership, such as circumstances
for creating alliances between private and public actors from a strategy perspective, explore the impact of incentive mechanisms and risk management procedures on health
service performance throughout the extended project life-cycle, and to create conducive environments to foster inter-project learning
- …