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Velocity Control of Trapped Ions for Transport Quantum Logic Gates


R. Oswald

Master Thesis, FS15 (10441)

While quantum information processing with trapped ions has already been demonstrated at high fidelities with a few ions, scaling up to larger numbers is a formidable challenge. For doing so, the quantum CCD architecture proposes interconnecting many small ion traps and transporting ions between processing and storage regions [Wineland 98, Kielpinski 02]. More recently, transport quantum logic gates have been proposed to reduce the demands on the optical control [D. Leibfried 07]. Transport is therefore a key technique associated with scaling. In this work, we implement adiabatic ion transport, paying special attention to keeping the transport velocity constant over time. We present a method based on quadratic programming to calculate feedforward control inputs for transport, taking common hardware constraints into account. We also identify and eliminate a aw in our electronics used to implement transport. We then evaluate the use of iterative learning control to further improve the time-varying feedforward control inputs driving transport. With it, we have reduced velocity uctuations from 0:1m=s to 0:01m=s at an overall transport speed of 2:8m=s, paving the way for future experiments. We also present a new method to infer the time-dependent Hamiltonian of a two level system from straightforward experimental measurements. We use it to study the Hamiltonian arising during a transport gate with 40Ca+ , inferring both the ions velocity and the laser beam intensity it experiences over time.

Supervisors: Ludwig de Clercq (Trapped Ion Quantum Information Group, Physics Dep.), Amin Rezaeizadeh, Jonathan Home (Trapped Ion Quantum Information Group, Physics Dep.), Roy Smith


Type of Publication:

(12)Diploma/Master Thesis

R. S. Smith

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% Autogenerated BibTeX entry
@PhdThesis { Xxx:2015:IFA_5338
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