Equation 10 · Part 2 · The Entry a Relabeling Cannot Write
Symbol ρ
What this part means
ρ is an argument of the function-like quantity on the left; its role is set by that function’s stated inputs.
Its job in the formula
ρ is an argument of the function-like quantity on the left; its role is set by that function’s stated inputs.
Full expression→Symbol ρ→Article meaning
The passage around this formula
A coarse description reports less. It is built from a completely positive, trace-preserving map , a quantum channel sending fine states to coarse states, together with a coarse Hilbert space and a Hermitian coarse Hamiltonian on it. The simplest case is the partial trace over the bath, = [] with = ; nothing below depends on that particular choice, and a passive relabeling built from no discarding at all, treated next, is a channel too.
Learn the underlying idea
A variable is a named place for a value. Its letter is a local label: x can mean position in one formula and a data point in another.
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Sources cited in the article section
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