On the ideas and methods of the solid spin-state qubit entanglement. The quantum entanglement between two system
We will be interested in two directions of entanglement of spin-electron states, spin-electron-photon states, spin-electron-nuclear states in a system of two solid-state qubits, respectively, divided both into (a) into small and (b) into sufficiently long distances. It is well known that these areas correspond to the two most important practical goals in quantum information - the development of quantum computers and the implementation of quantum teleportation over long distances. In the past few years, the first pioneering results on the entanglement of the spin-electronic states of two NV-centers have already been obtained in these directions, in one experiment, located at a distance of 25 nm at room temperature (a), and in the other, three meters distant from each other under conditions of low cryogenic temperatures. Modern nano-technological advances in integrated optics and electronics, together with the use of electrons and photons as quantum links and nuclear spins for quantum processing and memory, opens the way to the implementation of solid-state quantum networks, which, in order to obtain stronger effects of spin states of two or more solid-state qubits at remote distances, should include further progress of the very ideas and methods of quantum entanglement dynamics of composite spin-electron and spin-nucleus states in the framework of the apparatus of density matrices.