A symmetric 1 to 2 quantum cloning machine (QCM) is presented that provides
high-fidelity copies with 0.90β€Fβ€0.95 for all pure (single-qubit)
input states from a given meridian of the Bloch sphere. \cor{Emphasize is
placed especially on the states of the (so-called) Eastern meridian, that
includes the computational basis states \ketm{0}, \ketm{1} together with the
diagonal state \ketm{+} = \frac{1}{\sqrt{2}} (\ketm{0}
+ \ketm{1}), for which suggested cloning transformation is shown to be
optimal.} In addition, we also show how this QCM can be utilized for
eavesdropping in Bennett's B92 protocol for quantum key distribution with a
substantial higher success rate than obtained for universal or equatorial
quantum copying.Comment: 2 figures, 20 reference