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Barium Magnesium Alloy as Source of Atomic Ba for Ion Trapping

Jane Gunnell, Thomas Griffiths, Boris B. Blinov

Abstract

Trapped atomic ion qubits exhibit long coherence times and high fidelity qubit state preparation, manipulation and detection, making them well-suited for scalable quantum computing applications. Among several atomic species used in quantum computing and other application, singly-charged ions of barium stand out due to their long wavelength transitions and the presence of very long-lived metastable internal states. However, elemental barium is a highly reactive metal making it experimentally difficult to work with when making atomic beam sources. In this paper, we demonstrate a method of using resistively heated ovens loaded with a barium magnesium alloy (BaMg) as a source of barium for ion traps. This alloy is not very chemically reactive and does not oxidize in air. We found that a sample of BaMg in a resistively heated oven produced barium vapor pressures on the same order as a metallic barium sample prepared the same way. Two separate ovens, one with a sample of BaMg and one with metallic barium, were used as source for an ion trap. We observed reliable trapping of 138Ba+ ions both with the elemental barium source, and the BaMg source.

Barium Magnesium Alloy as Source of Atomic Ba for Ion Trapping

Abstract

Trapped atomic ion qubits exhibit long coherence times and high fidelity qubit state preparation, manipulation and detection, making them well-suited for scalable quantum computing applications. Among several atomic species used in quantum computing and other application, singly-charged ions of barium stand out due to their long wavelength transitions and the presence of very long-lived metastable internal states. However, elemental barium is a highly reactive metal making it experimentally difficult to work with when making atomic beam sources. In this paper, we demonstrate a method of using resistively heated ovens loaded with a barium magnesium alloy (BaMg) as a source of barium for ion traps. This alloy is not very chemically reactive and does not oxidize in air. We found that a sample of BaMg in a resistively heated oven produced barium vapor pressures on the same order as a metallic barium sample prepared the same way. Two separate ovens, one with a sample of BaMg and one with metallic barium, were used as source for an ion trap. We observed reliable trapping of 138Ba+ ions both with the elemental barium source, and the BaMg source.
Paper Structure (6 sections, 2 figures)

This paper contains 6 sections, 2 figures.

Table of Contents

  1. Introduction
  2. Oven flux testing
  3. Trapping Ba ions
  4. Discussion
  5. Outlook
  6. Acknowledgements

Figures (2)

  • Figure 1: (a) A BaMg sample approximately 5 cm on each side. (b) An example of a stainless steel oven used in the preliminary testing of the BaMg as neutral Ba source.
  • Figure 2: Results from BaMg testing using a residual gas analyzer (RGA). The data points from the BaMg sample are averaged over three independent heating cycles. The 24 a.m.u. signal, corresponding to magnesium, exhibits a higher partial pressure at lower temperatures. In contrast, the 138 a.m.u. signal, corresponding to barium, increases with temperature but reaches a comparatively lower peak pressure. However, at higher temperatures, the 138 a.m.u. signal from the BaMg sample is on the same order of magnitude as that measured from a metallic barium sample. This suggests that BaMg can serve as a viable substitute for metallic barium as a barium source. The inset shows representative data recorded directly from the RGA during a single BaMg heating cycle. The oven current was increased in increments of 0.5 A to 1 A at several times during the heating cycle.