A single bichromatic field near resonant to a qubit transition is typically used for σx or σy Mølmer-Sørensen-type interactions in trapped-ion systems. Using this field configuration, it is also possible to synthesize a σz spin-dependent force by merely adjusting the beat-note frequency. Here, we expand on previous work and present a comprehensive theoretical and experimental investigation of this scheme with a laser near resonant to a quadrupole transition in Sr+88. Further, we characterize its robustness to optical phase and qubit frequency offsets, and demonstrate its versatility by entangling optical, metastable, and ground-state qubits.
