QUANTUM DECOHERENCE

Bloch sphere, environment coupling, coherence decay, pointer states

QUBIT STATE

θ (polar)
φ (azimuthal)
|⟨0|ψ⟩|²1.00
|⟨1|ψ⟩|²0.00
Coherence |ρ₀₁|0.00
Purity Tr(ρ²)1.00

ENVIRONMENT

INITIAL STATE

CONTROLS

POINTER STATES

Pointer states: eigenstates of interaction Hamiltonian H_int
For σ_z coupling → |0⟩,|1⟩ are pointer states
Superpositions decohere → classical mixture
τ_D = 1/γ for pure dephasing
Decoherence time τ_D