Sorry for the dumb question. Some ions used in quantum computing are Yb171+, Be9+, Ca43+.

According to this ionic numenclature, "We have seen that some elements lose different numbers of electrons, producing ions of different charges (Figure 3.3). Iron, for example, can form two cations, each of which, when combined with the same anion, makes a different compound with unique physical and chemical properties. Thus, we need a different name for each iron ion to distinguish Fe2+ from Fe3+. The same issue arises for other ions with more than one possible charge."

But now my question is, what does it mean then the numbers in the elements of the examples I have written above? For instance, calcium has 20 protons, neutrons and electrons, so it can't lose 43 electrons... What does it mean then the above notation?


1 Answer 1


The numbers you are seeing are labeling the isotope, not the charge. For example, they are specifying the isotope of calcium that has 43 nucleons. Since calcium by definition has 20 protons, this means the isotope used has 23 neutrons. Wikipedia says that this isotope is one of the 5 stable isotopes of calcium, so even if it's not as common as $^{40}$Ca it's still usable.

It's more clear with a notation with the isotope number written before the letters, like ${}^{43}$Ca$^+$, but you'll have to deal with whatever a source tells you. Good to keep your question in mind - since you know calcium won't be losing 43 electrons, you know that number must be the isotope number.

  • $\begingroup$ And then what does the + means? Losing of just one electron? $\endgroup$ Jan 22 at 15:50
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    $\begingroup$ @user2820579 yes. The idea is that something like calcium has two valence electrons, so if it loses one electron it becomes ionized (such that it can be moved around by electric fields) and it now has a single valence electron that behaves in many ways like the electron of a hydrogen atom (so you can have Rydberg ions, if you want) $\endgroup$ Jan 22 at 16:52
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    $\begingroup$ @user2820579 e.g., read Ion Trap Quantum Computing with Ca+ Ions and see that they use the notation I mentioned and they compare the merits of $^{40}$Ca$^+$ and $^{43}$Ca$^+$ $\endgroup$ Jan 22 at 16:54

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