Experiments with Trapped Ions: Entanglement, Novel Traps, and Quantum Jumps

Abstract

Quantum computing promises to revolutionize modern computation. The race to establish a reliable quantum computing system has spurred research over the globe with the goal of establishing a reliable qubit system. One of the more promising candidates are trapped ions. To that end, I have characterized, improved, and designed experiments to be performed in a novel parabolic mirror ion trap. We measured the trap to have a light collection efficiency of 39%, nearly an order of magnitude higher than the light collection of ion traps utilizing standard collection optics. The parabolic mirror also improves the quality of image collected from a trapped ion, but is limited by the micromotion the ion undergoes while at the optical focus. We designed a new trap component to allow radial control over the ion position by moving the RF null, instead of displacing it with DC bias plates. This improved trapping system is a key part of our plan to to remotely entangle an In donor defect in ZnO with a single trapped Yb+ using a 369 nm photon bus. The lifetime of the relevant ionic state is longer than that of the ZnO system by a factor of 6, leading to a greatly decreased temporal overlap in their emitted photons and thus decreased fidelity in the final entangled state if left unattended. This temporal mismatch is a long outstanding challenge when entangling disparate quantum systems, and to address it I performed numerical calculations to design an excitation pulse which can shape the emitted In photon to have an overlap of 0.99 with the Yb+ photon. This leads to a calculated entangled state fidelity of 94% and an entangled state generation rate of 21 kHz with reasonable experimental parameters. Future directions of the parabolic mirror project are the construction of an ellipsoidal mirror trap which is expected to collect light from 95% of the solid angle surrounding a trapped ion. This high light collection will enable investigations into the time dynamics of quantum jumps. These jumps occur when a weakly driven system is continuously measured, and their appearance is entirely random. However, recent work in an artificial superconducting atom suggests that there is a latency period in other transitions which precedes a jump, allowing for these events to be 'caught'. We endeavor to confirm this behavior in a trapped ion, confirming the discovery for a real atomic system.