Abstract
General requirements for the materials for systems and devices whose operation is based on quantum correlations are discussed. The fluctuation theory of quantum entanglement is outlined. This theory allows one to estimate the size of the region of weak fluctuations of quantum entanglement for spin dimers in various materials. The concept of quantum discord as a measure of pure quantum correlations is outlined. Quantum correlations in polycrystalline samples of binuclear nitrosyl iron complexes were estimated from the temperature dependences of the magnetic susceptibilities. Particular attention is paid to calculations of the temperature corresponding to the emergence of quantum entanglement. Methods for increasing this temperature are discussed. The problem of the quantum information transmission as well as the future development of quantum technology is considered. The bibliography includes 120 references.