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Equation 21 · Part 7 · The Entry a Relabeling Cannot Write

subscript

DΛ:=Hf−Λ†(Hc).D_\Lambda := H_f - \Lambda^\dagger(H_c).
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

That pullback is the object this article is built around: DΛ:=Hf−Λ†(Hc)D_\Lambda := H_f - \Lambda^\dagger(H_c). 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.

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the article section

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