QUANTUM DECOHERENCE — Zurek Einselection & Pointer Basis

Watch a quantum superposition lose coherence as environment entanglement selects the "pointer basis"
DENSITY MATRIX ρ (system)
WIGNER FUNCTION (phase space)
0.00 0° 0°
Einselection (Zurek 1981): Environment interaction selects the pointer basis — states that remain stable under monitoring. Off-diagonal elements of ρ (quantum coherences) decay as e−γt, leaving a classical mixture. Decoherence time: τ_D = τ_relax / (Δx/λ_dB)² — macroscopic objects decohere in ~10−23s.