Spins and Ladders: Building Qubit-Boson Computing in the QSCOUT Trapped-Ion Testbed

Quantum resources beyond two levels of a qubit, such as qudits or coupled bosonic modes, offer a promising route toward more efficient quantum computing resource allocation. In particular, bosonic modes provide access to a quasi-continuous variable ideal for more efficient simulations of bosonic systems. Hybrid qubit-boson architectures are seen in various qubit modalities such as superconducting qubits coupled to microwave resonators and neutral atoms in tweezers, but trapped ions are a natural candidate as the collective motion of the chain results in quantized modes. Here, we describe efforts to develop a universal qubit-boson gateset in Sandia’s trapped-ion testbed, the Quantum Scientific Computing Open User Testbed (QSCOUT). This proof-of-principle gateset includes a Jaynes-Cummings (JC) and anti-JC gate, conditional displacement gate, beamsplitter gate, and conditional rotation gate within a two-ion chain. With this control, we describe progress in several demonstrations such as simulating the Generalized Resonant Rabi model and static Yukawa model, as well as observing Aharanov-Anandan phase. We also discuss efforts to benchmark and generalize the gateset to a larger register of ions and motional modes.