Quantum Information

Scaling up the Hilbert space of a quantum computer is essential to demonstrate quantum advantage over classical computing. Other than packing more quantum information carrier in a quantum computing system, one avenue for increasing the quantum computing Hilbert space is by encoding more logical states per quantum information carrier (making it a qudit), rather than a traditional 2-state qubit encoding. Trapped ions typically exhibit multiple (meta)stable electronic energy states that are suitable for logical state encodings and are a suitable platform for qudit applications. In this talk, I present our work on realizing a 25-level trapped 137Ba+ ion qudit, which is the maximal encoding allowed by the single-shot readout protocol that we employ. We show that the harnessing of these additional logical states per ion can be done by just adding a few more lasers to the control system, without any trapping architecture modification compared to a qubit system. I will also present the experimental challenges and limitations, fundamental and technical, relevant to realizing a 25-level trapped 137Ba+ ion qudit.