QuantumClassicalCrossover
plain-language theorem explainer
QuantumClassicalCrossover packages the four parameters that control the continuous quantum-to-classical transition inside the Recognition Science J-cost model. Workers modeling decoherence in many-body systems cite the structure when they need to vary system size N, temperature T, coupling strength, and decoherence time tau_D together. The declaration is a bare record definition whose only content is the four fields plus an inline remark on ledger coarse-graining.
Claim. A structure consisting of a natural number $N$ (number of particles), a real number $T$ (environment temperature), a real number $g$ (coupling strength), and a real number $tau_D$ (decoherence time).
background
The module QF-011 derives classical emergence from many-body J-cost minimization. Single-particle superpositions carry low J-cost while correlated many-body superpositions carry J-cost quadratic in N; for large N the minimum is therefore attained by product states. The structure collects the external knobs that tune the location of this minimum: system size, temperature, coupling, and the resulting decoherence timescale.
proof idea
The declaration is a direct structure definition with zero proof lines; it simply records the four fields N, T, coupling, and tau_D together with a comment block on RS ledger coarse-graining.
why it matters
The definition supplies the parameter interface required by the QF-011 derivation that classical behavior arises when product states minimize total J-cost. It therefore sits inside the Recognition Science program that obtains all physics from the single J-functional equation and the phi-ladder. No downstream theorems yet consume the structure.
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