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Equation 23 · Part 1 · The Entry a Relabeling Cannot Write

Symbol H_f

Hf\mathcal H_f
HfH_f

What this part means

HfH_f is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

Its job in the formula

HfH_f is a part of this expression. Its role is fixed by the surrounding article and by the operations shown in the formula.

The passage around this formula

DΛD_\Lambda is Hermitian on Hf\mathcal H_f — a positive, unital map applied to a self-adjoint input stays self-adjoint — and it carries units of energy, since both terms do. Its state-dependent reading,

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Learn the underlying idea

A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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Sources cited in the article section

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