Speaker
Description
Trapped atomic ions are one of the most promising quantum computing architectures. They exhibit all of the primitives necessary for building a quantum computer and have very few fundamental limitations to the achievable gate fidelities. While high-fidelity quantum logic has already been demonstrated on a small number of qubits, scaling up the system without compromising its performance remains challenging. Here we present the design and initial evaluation of a quantum system aimed at realising high-precision control over long chains of $^{133}\mathrm{Ba}^+$ ions.
Barium ions exhibit several features that are favourable for quantum computing experiments, including visible-light optical transitions and very long-lived metastable states. The $^{133}\mathrm{Ba}^+$ isotope is particularly interesting as it additionally offers a range of magnetically insensitive 'clock' qubit states in the ground level and in the metastable $D_{5/2}$ level, and optical `clock' qubits spanning the $S_{1/2}-D_{5/2}$ manifolds [1]. Hence it opens a vast playground of novel qubit control schemes, including qubit hiding, partial projective measurements and mid-circuit measurements.
In our experiment we use a segmented monolithic 3D microfabricated trap [2] that provides a high degree of control of the trapping potential whilst maintaining a low heating rate. We show preliminary results on the trap characterisation performed with $^{138}\mathrm{Ba}^+$ ions.
The ground level qubit transition of $^{133}\mathrm{Ba}^+$ is driven by a two-photon Raman process using a $532\;\mathrm{nm}$ laser. We present the design and initial characterisation of our novel system for driving this $10\;\mathrm{GHz}$ transition with low phase and intensity noise. We further discuss the design of a laser-written waveguide device used for individual addressing of non-uniformly spaced ion crystals.
[1] J. E. Christensen, D. Hucul, W. C. Campbell, and E. R. Hudson. High-fidelity manipulation of a qubit enabled by a manufactured nucleus.npjQuantum Information, 6(1):35, 2020.
[2] P. See, G. Wilpers, P. Gill, and A. G. Sinclair. Fabrication of a monolithicarray of three dimensional si-based ion traps.Journal of Microelectrome-chanical Systems, 22(5):1180–1189, 2013.
