  We investigate the decay of two-qubit entanglement caused by the influence of
classical noise. We consider the whole spectrum of cases ranging from
independent to fully correlated noise affecting each qubit. We take into
account different spatial symmetries of noises, and the regimes of noise
autocorrelation time. The latter can be either much shorter than the
characteristic qubit decoherence time (Markovian decoherence), or much longer
(approaching the quasi-static bath limit). We express the entanglement of
two-qubit states in terms of expectation values of spherical tensor operators
which allows for transparent insight into the role of the symmetry of both the
two-qubit state and the noise for entanglement dynamics.
