Open RQC colloquium. Lecture 38

Abstract

Reasons for using methods of nuclear magnetic resonance (NMR) in problems of quantum informatics are discussed. Special attention is paid to solid state NMR for quantum information processing. Quantum entanglement and quantum discord as measures of quantum correlations are considered in detail. One-dimensional systems of spins connected by the XY-Hamiltonian (chains and rings) are studied. In particular, we worked out a method of exact diagonalization of the XY-Hamiltonian in alternating open spin chains. That method is used for an investigation of quantum correlations in dimer systems. In the simplest multi-pulse experiment, multi-pulse spin locking, methods of calculation of quantum discord are developed both for low and high temperatures. A condition of the emergence of quantum correlations in the multi-pulse spin locking is obtained for two-spin systems. Quantum correlations are investigated in multiple quantum (MQ) NMR for two-spin systems. A theory of dipolar relaxation of MQ NMR coherences is developed for one-dimensional systems. The theoretical predictions agree with the obtained experimental data. It is shown that the relaxation of the MQ NMR coherence of the second order can be considered as a model of decoherence in many-qubit coherent clusters. The dependence of the decoherence rate on the number of spins is also obtained. 

Biography

Edward Feldman was born in 1947 in Port Arthur (China). He graduated from Moscow Institute of Technology summa cum laude in 1971 and obtained his Ph.D. in chemical physics (1976) at the Institute of Chemical Physics of RAS. After finishing Ph.D. he dealt with problems of dynamics and thermodynamics of nuclear spin systems in solids. He worked out (with Professor B.N.Provotorov) the thermodynamic theory of multi-pulse NMR experiments.  E. Feldman investigated the convergence of the Magnus expansion in systems with periodically oscillating external fields. He obtained his Dr. Sci. degree in chemical physics in 1992 (Chernogolovka). Since 1994 he works in the field of the theory of multiple quantum NMR in solids. He worked  as a visiting professor in Sherbrooke University (Canada) in 1995-1997. E. Feldman was invited to the laboratory of Richard  Ernst, Nobel Prizer in Chemistry, (Zurich, ETH) in 1998. In the present time he is working as a chief of the theoretical department of the Institute of Problems of Chemical Physics. His current scientific interests are the theory of magnetic resonance and an application of the magnetic resonance methods to problems of quantum informatics.

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