Transmissão de emaranhamento através de cadeias de spins

Abstract

In this thesis we studied the transmission of entangled states in unmodulated spin chains using a slight modification in the XY isotropic model (XX model) that describes a one-dimensional spin-1/2 chain. We have shown that it is possible to transmit bipartite entangled states from a sender to a receiver with high fidelity from one end of the chain to the other. This transmission occurs without the need for external fields or modulation of the coupling constants between the qubits, which simplifies its pratical implementation. We verified, through numerical analysis, that the modification in the one-dimensional model works for any size of the chain. We also verified that the proposed model is robust for small imperfections in the coupling constants, low magnetic field noise and residual interection between spins in the z direction. At last, we analyzed whether the proposed model can also be used as a transmitter of single qubit states and we discussed these results within the context of the quantum information theory.