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In several papers and contexts I've seen this phrases like this used:

The nitrogen-vacancy in diamond is an atom-like system in the solid state.

What does "atom like system" mean exactly? I've done a google search and turned up little. It seems to be a field specific term. My guess is that the system of (for example) a nitrogen and vacancy pair can be modeled together using standard atomic model (like the standard hydrogen atom system that's studied in QM).

An explanation of what it specifically means, i.e. what assumptions you can make about the system that defines it as "atom like" would be appreciated.

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    $\begingroup$ I know sometimes people describe superconducting circuits as like "artificial atoms." See for example here: nature.com/nature/journal/v474/n7353/full/nature10122.html . Maybe this is the same idea. All it means in that case is that the system is a quantum system with discrete, unevenly spaced energy levels, and I've always found it to be a rather annoying piece of jargon. $\endgroup$
    – Rococo
    Commented Feb 23, 2017 at 22:19
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    $\begingroup$ $\uparrow$ Which papers? $\endgroup$
    – Qmechanic
    Commented Feb 23, 2017 at 22:34
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    $\begingroup$ @Rococo I'm a practicing member of the superconducting qubit field, and I too find that particular piece of jargon to be unhelpful and even counterproductive. I can't tell you how many times I've seen researchers start a talk about superconducting qubits with a cartoon of an atom in a Fabrey-Perot cavity and thought to myself "You're talking to a room of circuit people, so why are you trying to introduce your work with a diagram from AMO?". $\endgroup$
    – DanielSank
    Commented Feb 23, 2017 at 22:44
  • $\begingroup$ @Rococo Mind you, a "quantum system with discrete uneven energy spectrum" is a notion that could do with a good, succinct moniker in some applications and discussions. $\endgroup$ Commented Feb 23, 2017 at 23:28
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    $\begingroup$ @sammygerbil To be frank, the phrase is common enough that no reference is really needed here. $\endgroup$ Commented Feb 27, 2017 at 15:35

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An "atom-like" solid state system is a many-body system that has a discrete energy spectrum resembling to an atomic system (e.g. hydrogen atom).

There are many examples such as quantum dot, or NV centre in diamond. Some people even refer them as 0-dimensional system.

Under some circumstances, one could consider a quantum dot effectively as an electron in a parabolic potential, thus its energy spectrum is quantised, similar to a hydrogen atom. In fact, there are thousands/millions of electrons in the quantum dot, but they behave like one.

More details: von Delft's lecture notes

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    $\begingroup$ I think this answer would be improved if you added something about nonlinearity/anharmonicity. Much of the time when I see "artificial atom" there's a contrast drawn with oscillator systems. $\endgroup$
    – zeldredge
    Commented Feb 27, 2017 at 15:34
  • $\begingroup$ Thanks for your comment. I totally agree with you that in reality one can never encounter a system with an exact harmonic-oscillator-like behaviour. I'm not an expert on this issue, perhaps some lecture notes would be helpful. $\endgroup$
    – Exhaustive
    Commented Feb 27, 2017 at 16:07

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