Coherent interactions and thermometry in a trapped ion quantum simulator
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Date
2022-10-27
Authors
Vogliano, Anthony
Journal Title
Journal ISSN
Volume Title
Publisher
University of Waterloo
Abstract
Quantum simulators are useful tools to study exotic systems which may be otherwise
intractable for a traditional computer. In particular, the trapped-ion platform has been a
leading candidate for use in quantum simulation experiments because of its high fidelity
state-preparation and measurement operations and its all-to-all connectivity. The relative
difficulty of interacting with the long lived hyperfine states of 171Yb+ ions make them
excellent choices for encoding information as the isolation creates stability against a noisy
environment. Maintaining coherence for such a long time opens the door for complex
coherent interactions, which are a backbone of quantum simulation experiments. One of
the most critical coherent operations for a trapped-ion quantum simulator is the entangling
Molmer-Sørenson interaction.
Building up to the Molmer-Sørenson interaction requires fine control over not just the
state of the quantum register, but also the motional state of the ion. For this reason,
cooling to near the ground state of motion is crucial to obtaining high fidelity experiments.
Characterizing the temperature in such systems can prove challenging, requiring coherent
techniques.
In this thesis, I describe my work towards preparing a Molmer-Sørenson interaction
for a 171Yb+ trapped ion quantum simulator. I detail the methods used to bring-up the
coherent Raman interactions, and characterize the Doppler cooling and Continuous Side-
band Cooling (CSBC) techniques we use, their implementations on our system, and their
limitations. I characterize the temperature of our ions before and after CSBC using coher-
ent methods, showing a 46x improvement in the motional state population and confirming
that post-CSBC the ions are in the Lamb-Dicke regime. I also summarize my efforts in
constructing a future ”blade trap” system with enough precision in the alignment of the
electrodes to eventually enable efficient cooling. I show preliminary evidence that 5um
precision in blade position should be feasible.
Description
Keywords
Quantum Information, Ytterbium, Sideband Cooling, Thermometry, Trapped Ions, Quantum Simulator