Decoherence and entanglement in spin environment

Full text: Creating and preserving coherent spin states of electron are essential tasks for spintronics applications. At low temperatures decoherence of quantum states due to spin-spin interactions play a major role. For example, in quantum dots the hyperfine coupling provides an important mechanism for decoherence. Similarly, in molecular magnets it is believed that the bath of nuclear spins rapidly destroys coherence even at very low temperatures. In this work, using a very simple and analytically solvable model, we first study decoherence of a single central spin due to a spin bath. Next, we examine how a two spin system loses its coherence. In this case we also investigate how the entanglement changes. We compare single bath and two bath cases