Photon echo quantum RAM integration in quantum computer

We have analyzed an efficient integration of the multi-qubit echo quantum memory into the quantum computer scheme on the atomic resonant ensembles in quantum electrodynamics cavity. Here, one atomic ensemble with controllable inhomogeneous broadening is used for the quantum memory node and other atomic ensembles characterized by the homogeneous broadening of the resonant line are used as processing nodes. We have found optimal conditions for efficient integration of multi-qubit quantum memory modified for this analyzed physical scheme and we have determined a specified shape of the self temporal modes providing a perfect reversible transfer of the photon qubits between the quantum memory node and arbitrary processing nodes. The obtained results open the way for realization of full-scale solid state quantum computing based on using the efficient multi-qubit quantum memory.Comment: 13 pages, 5 figure

Photon echo quantum memory with complete use of natural inhomogeneous broadening

The photon echo quantum memory is based on a controlled rephasing of the atomic coherence excited by signal light field in the inhomogeneously broadened resonant line. Here, we propose a novel active mechanism of the atomic rephasing which provides a perfect retrieval of the stored light field in the photon echo quantum memory for arbitrary initial inhomogeneous broadening of the resonant line. It is shown that the rephasing mechanism can exploit all resonant atoms which maximally increases an optical depth of the resonant transition that is one of the critical parameters for realization of highly efficient quantum memory. We also demonstrate that the rephasing mechanism can be used for various realizations of the photon echo quantum memory that opens a wide road for its practical realization.Comment: 6 pages, 4 figure

APPLICATION OF THE THEORY OF LATENT VARIABLES TO PERSONNEL MANAGEMENT METHODS

One of the main tasks of the human-resources (HR) department is the qualitative management of personnel, which is the basis for effective work of the organization. The paper presents models of personnel management based on the theory of latent variables. Research objective is to use the Rasch model for assessing latent variables to evaluate the competence of employees and  their suitability for certain positions and also quality control of their work.Three problems of personnel management are considered.Organization of qualitative selection of candidates for vacancies by objective assessment of the degree of professional suitability of candidates with a view to selecting the best employees. Multilateral monitoring as the quality of performance of duties of each employee on the one hand, and the efficiency of the work of the whole team on the other. A dynamic comparison is made between the quality of performance of their duties in different periods of time. Effective appointments of specific employees to certain positions. Based on the criteria of the employee's suitability for certain positions, the integral degree of the employee's suitability for each vacancy is calculated. In addition, the model makes it possible to assess the degree of influence of the criteria on the evaluation of employees.The models proposed in the paper allow obtaining estimates on a linear interval scale, which can be translated into any other scale, for example, probabilistic. Estimates do not depend on a set of criteria and the set of evaluated employees.

Fast and robust two- and three-qubit swapping gates on multi-atomic ensembles in quantum electrodynamic cavity

Creation of quantum computer is outstanding fundamental and practical problem. The quantum computer could be used for execution of very complicated tasks which are not solvable with the classical computers. The first prototype of solid state quantum computer was created in 2009 with superconducting qubits. However, it suffers from the decoherent processes and it is desirable to find more practical encoding of qubits with long-lived coherence. It could be single impurity or vacancy centers in solids, but their interaction with electromagnetic radiation is rather weak. So, here, ensembles of atoms were proposed for the qubit encoding by using the dipole blockade mechanism in order to turn multilevel systems in two level ones. But dipole-dipole based blockade introduces an additional decoherence that limits its practical significance. Recently, the collective blockade mechanism has been proposed for the system of three-level atoms by using the different frequency shifts for the Raman transitions between the collective atomic states characterized by a different number of the excited atoms. Here, we propose two qubit gate by using another collective blockade mechanism in the system of two level atoms based on exchange interaction via the virtual photons between the multi-atomic ensembles in the resonator. Also we demonstrate the possibility of three qubit gate (Controlled SWAP gate) using a suppression of the swap-process between two multi-atomic ensembles due to dynamical shift of the atomic levels controlled by the states of photon encoded qubit