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Equation 131 · Part 1 · The Entry a Relabeling Cannot Write

Symbol H_c

Hc(t)=Hf+iℏ(iωr2σz)=ℏ(ω0−ωr)2σz,H_c(t) = H_f + i\hbar\Big(i\frac{\omega_r}{2}\sigma_z\Big) = \frac{\hbar(\omega_0 - \omega_r)}{2}\sigma_z,
HcH_c

What this part means

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

Its job in the formula

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

The passage around this formula

…Rabi used to analyze spin behavior in a gyrating magnetic field in 1937 [ 14 ] . Two checks confirm the recovery is exact rather than incidental: at ωr\omega_r = 0 , the non-rotating case, Δframe\Delta_{\rm frame} ≡\equiv 0 and HcH_c = HfH_f , the already-verified baseline; at ωr\omega_r = ω0\omega_0 , exact corotation, HcH_c = 0 and the spin’s energy in this frame vanishes identically, which is the ordinary resonance condition, not a puzzle, because Δframe\Delta_{\rm frame} = -ℏ\hbarω0\omega_0⟨\langleσz\sigma_z⟩\rangle/2 exactly cancels the…

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