Equation 76 · Part 5 · The Entry a Relabeling Cannot Write

subscript

H_S = (\hbar\omega/2)\sigma_z^S

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.

Full expressionsubscriptArticle meaning

The passage around this formula

A single exactly solvable case makes the ledger’s behavior concrete, and it is worth being explicit that what follows is an analytic evaluation of a stated model, not a simulation and not a measurement. Let S and B each be a two-level system — a spin, in the sense this literature uses the word for any two-state quantum degree of freedom — with bare Hamiltonians $H_S$ = ( $\hbar$ $\omega$ /2) $\sigma_z^S$ and $H_B$ = ( $\hbar$ $\omega$ /2) $\sigma_z^B$ tuned to the same frequency $\omega$ , coupled by an excitation-conserving exchange term,

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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

[12] Circuit Quantum Electrodynamics ↗

These citations provide research context; check each source for the exact claim it supports.