Quantum Decoherence
The loss of quantum coherence where interaction between a quantum system and its macro-environment converts a quantum superposition into a classical probabilistic mixture.
Governing formula
ρ_offdiag(t) = ρ_offdiag(0) e^(-t / τ_dec)
SI unit
s (Decoherence Time Constant)
In depth
Decoherence explains how classical macroscopic reality emerges from quantum mechanics. Environmental entanglement rapidly suppresses off-diagonal phase interference terms in the system's density matrix, dissipating quantum superpositions without violating the Schrödinger equation.
Examples in the real world
Environmental thermal noise causing quantum bit (qubit) state errors in quantum computers, requiring active quantum error correction.