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Equation 69 · Part 1 · The Entry a Relabeling Cannot Write

Symbol Δ E_Lambda

ΔEΛ(ρ)=Eb\Delta E_\Lambda(\rho) = E_b
ΔEΛ\Delta E_\Lambda

What this part means

Δ ELE_Lambda is part of the quantity the equation computes from the expression on the right.

Its job in the formula

Δ ELE_Lambda is part of the quantity the equation computes from the expression on the right.

The passage around this formula

…First, an uncorrelated, non-interacting bath: set HSBH_{SB} = 0 and let ρ\rho = ρS\rho_S ⊗\otimes |b⟩\rangle⟨\langle b| for any system state ρS\rho_S and any bath eigenstate |b⟩\rangle with HBH_B|b⟩\rangle = EbE_b|b⟩\rangle . Then Δ\Delta EΛ(ρ)E_\Lambda(\rho) = EbE_b for every choice of ρS\rho_S whatsoever — a pure constant, entirely independent of what the system is doing, unambiguously assignable to a named, located pile of energy sitting in a part of the world the coarse description agreed in advance not to look at. Nothing is…

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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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