  The decoherence of a localized electron spin in a lattice of nuclear spins is
an important problem for potential solid-state implementations of a quantum
computer. We demonstrate that even at high fields, virtual electron spin-flip
processes due solely to the hyperfine interaction can lead to complex nuclear
spin dynamics. These dynamics, in turn, can lead to single electron spin phase
fluctuation and decoherence. We show here that remarkably, a spin echo pulse
sequence can almost completely reverse these nuclear dynamics except for a
small visibility loss, thereby suppressing contribution of the hyperfine
interaction to T_2 processes. For small systems, we present numerical evidence
which demonstrates a universal scaling of the magnitude of visibility loss that
depends only on the inhomogeneous line width of the system and the magnetic
field.
