Allcock, DavidMetzner, Jeremy2024-08-072024-08-072024-08-07https://hdl.handle.net/1794/29752Encoding qubits in the electronic states of atoms has enabled the ability toperform computations, sense the environment, and gain a deeper understanding of other physical systems through quantum simulation. In the trapped ion platform, each of these applications is made possible, or enhanced by coupling the qubit to the motion of the trapped ions. The motion can be used to do more than just mediate interactions with qubits and is itself a resource for computation, sensing and simulation. The work presented here focuses on methods for manipulation and entanglement of trapped ion motional states in a spin-independent way while retaining the spin to enable measurement of the quantum state of the motion. We have shown the ability to use a set of spin-independent operations including displacement, beam splitter, squeezing and two-mode squeezing, to sense the phase of the oscillator states with precision exceeding the standard quantum limit (SQL) by up to 5.9 dB and approaching the ultimate Cram´er-Rao bound. With qubits still generally required for utilizing the motional states for quantum information experiments, qubit measurement makes it difficult to preserve any motional state during state detection. We have developed the technique of encoding both states in a metastable manifold which could enable methods to preserve particular motional states of longer-chains during state detection. We present preliminary results demonstrating this preservation of motional states using a mixed atomic-species trap at Lincoln Lab. The metastable encoding also provides the unique ability to engineer and explore non-Hermitian qubit Hamiltonians, where we have shown the ability to break the quantum speed limit.en-USAll Rights Reserved.quantum computingquantum sensingTrapped ionsElectronic Thesis or Dissertation