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Velocity Control of Trapped Ions for Transport Quantum Logic Gates

Author(s):

R. Oswald
Conference/Journal:

Master Thesis, FS15 (10441)
Abstract:

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

Year:

2015
Type of Publication:

(12)Diploma/Master Thesis
Supervisor:

R. S. Smith

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