  One of the most effective ways to advance the performance of quantum
computers and quantum sensors is to increase the number of qubits or quantum
resources in the system. A major technical challenge that must be solved to
realize this goal for trapped-ion systems is scaling the delivery of optical
signals to many individual ions. In this paper we demonstrate an approach
employing waveguides and multi-mode interferometer splitters to optically
address multiple $^{171}\textrm{Yb}^+$ ions in a surface trap by delivering all
wavelengths required for full qubit control. Measurements of hyperfine spectra
and Rabi flopping were performed on the E2 clock transition, using integrated
waveguides for delivering the light needed for Doppler cooling, state
preparation, coherent operations, and detection. We describe the use of
splitters to address multiple ions using a single optical input per wavelength
and use them to demonstrate simultaneous Rabi flopping on two different
transitions occurring at distinct trap sites. This work represents an important
step towards the realization of scalable integrated photonics for atomic clocks
and trapped-ion quantum information systems.
