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 $1.6\cdot 10^9$ 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