Ph.D. Thesis - Physics

Figure 9-12: Heating rate as determined by Doppler recooling for a series of ion-wire distances.
The heating rate is presented in quanta/s. Upon normalizing for the secular frequency,
the heating rate is roughly constant as the wire approaches.
we see.
9.4 Conclusions
Ion-ion coupling over a wire is an intriguing possibility for quantum networking. This could
find application in both quantum simulation and quantum computation. However, the
necessity of the wire being electrically floating at both dc and rf frequencies poses some
difficulty for this. The increase of secular frequencies as the wire approaches the ion is
detrimental to the coupling rate, and could even render the trap unstable if the frequencies
grow too high such that the q stability parameter approaches 0.9. In addition, stray charge
on the wire that does not discharge at a sufficient rate to ground influences the dc potential
seen by the ion, resulting in micromotion that must be compensated.
However, in these challenges lies an opportunity. A single trapped ion is an extremely
sensitive detector of electric fields. Perhaps measurements, such as those presented in this
chapter, may provide a way of measuring the capacitance of the wire, and the stray charge
that it holds. Such measurements would enable a more precise estimation of the wire-
mediated coupling rate, given its reciprocal dependence on the wire-ground capacitance.
The prospects for ion-ion coupling are still uncertain. It is fairly clear that the trap
potentials themselves will need to be reduced in magnitude as the wire approaches, and
the trap in a real sense becomes three-dimensional as opposed to surface-electrode in form.
Although traps of a 50 µm scale have been demonstrated, it has not been done with an
electrically floating electrode. In addition, although at the current ion-wire distance no
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