Spacing in Dirac's ket vector

I have defined myself a \ket which does \left| #1 \right\rangle. For a state with two numbers, say n and m, one writes, on paper, |a b>. What kind of distance should I use to separate those numbers? \, or more?

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Have you seen the braket package? (Not answering your question, just as an apropos.) –  Torbjørn T. Jun 12 at 18:00