Condensate fraction vs temperature; BEC as macroscopic quantum occupation
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Below T_c = (N/ζ(3/2))^(2/3) · h²/(2πmk_B), macroscopic condensation occurs into the ground state. The condensate fraction N₀/N = 1−(T/T_c)³ for T<T_c; the de Broglie wavelength exceeds the inter-particle spacing, and quantum statistics dominate.