Graduate Thesis Or Dissertation


Two-Species Ion Arrays for Quantum Logic Spectroscopy and Entanglement Generation Public Deposited
  • The quantum states of trapped atomic ions can be highly isolated from external perturbation, and precisely manipulated with applied laser fields. This makes them an excellent medium for quantum-limited experiments such as quantum information processing and precision spectroscopy. A relatively small number of ion species have been used for these types of experiments because most species are difficult to laser cool and detect directly. This thesis demonstrates a way to overcome this limitation by use of sympathetic cooling and state detection based on quantum logic. We apply these techniques to mixed-species arrays of Al+ and Be+ ions. A mathematical model for the motion of such a two-species array is presented in order to explore some features of the ion dynamics that are relevant for the experiments. Repetitive quantum nondemolition measurements of the electronic states of a Al+ ion show detection fidelities as high as 99.94 %. We also demonstrate the simultaneous detection of two Al+ ions and observe a detection fidelity of 99.8 %. The basic ideas behind the detection strategy are extended to potentially enable similar experiments on a more general class of atomic and molecular ions. We have also investigated, theoretically and experimentally, a method for preparing entangled Dicke states in trapped atomic ions. We consider a linear chain of N ion qubits that is prepared in a particular Fock state of motion. The m phonons are removed by applying a laser pulse globally to the N qubits, and converting the motional excitation to m flipped spins. The global nature of this pulse ensures that the m flipped spins are shared by all the target ions in a state that is a close approximation to the Dicke state. We calculate numerically the fidelity limits of the protocol and find small deviations from the ideal state for m = 1 and m = 2. We have demonstrated the basic features of this protocol by preparing the Bell state in two Mg+ target ions trapped simultaneously with an Al+ ancillary ion.
Date Issued
  • 2010
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Last Modified
  • 2019-11-17
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