DQC Seminar Series: Doing more with the same using metastable states of trapped ions

Today's most advanced ion trap quantum computers encode information in two level systems embedded in the ground state manifold or across an optical transition connecting the ground state to a metastable state. These architectures typically require a second ion species to perform mid-circuit measurement and sympathetic cooling without disturbing the data ions. To bypass this added system complexity, we can instead encode information entirely within a metastable manifold that is spectrally isolated from the ground-state fluorescence cycle. Most of the fundamental errors in this encoding can be converted into erasure errors, which allow for more efficient quantum error correction than Pauli errors. In this work, we describe recent results on high-fidelity entanglement between metastable qubits with integrated erasure conversion and measurement-based sympathetic cooling and ancilla readout in a mixed ground/metastable Coulomb crystal. Finally, we will discuss the derivation and demonstration of four- and six-photon Raman transitions for universal qudit control in the metastable manifold. --- Fall 2025 Seminar Dates: 4 Sep, 18 Sep, 2 Oct, 16 Oct, 30 Oct, 20 Nov, 4 Dec