  A M{\o}lmer-S{\o}rensen entangling gate is realized for pairs of trapped
$^{111}$Cd$^+$ ions using magnetic-field insensitive "clock" states and an
implementation offering reduced sensitivity to optical phase drifts. The gate
is used to generate the complete set of four entangled states, which are
reconstructed and evaluated with quantum-state tomography. An average
target-state fidelity of 0.79 is achieved, limited by available laser power and
technical noise. The tomographic reconstruction of entangled states
demonstrates universal quantum control of two ion-qubits, which through
multiplexing can provide a route to scalable architectures for trapped-ion
quantum computing.
