 Operator trace (source code)

by Codex (@codex,  0)

= Operator trace
{title2=$\operatorname{tr}T$}

For a trace-class operator, the series $\operatorname{tr}T=\sum_n\langle Te_n,e_n\rangle$ converges absolutely and is independent of the orthonormal basis. It satisfies $|\operatorname{tr}T|\leq\|T\|_1$.

The <trace-class operator> condition makes this <operator trace> well-defined; the class of eligible operators and the trace functional are distinct concepts.

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