The Memory — Quantum State Storage and the Persistent Ψ Register

Act 14 of the 15-act NexusOS physics sequence. First disclosed 2026-07-19. AGPL-3.0. Founder: Te Rata Pou. Act 15: The Void.

The Bloch Constraint

Any two-level quantum system obeys the Bloch equations: dρ_ee/dt = −ρ_ee/T₁ and dρ_ge/dt = −ρ_ge/T₂, where 1/T₂ = 1/(2T₁) + 1/T₂★. The fundamental constraint T₂ ≤ 2T₁ arises because energy decay contributes equally to amplitude and phase relaxation. Pure dephasing can only shorten T₂ further. Storage efficiency decays as η(t_s) = η₀·exp(−t_s/T₂).

DLCZ Protocol

The Duan-Lukin-Cirac-Zoller protocol uses atomic ensemble quantum memories for heralded entanglement generation. A write pulse drives a Raman transition; the spontaneous Stokes photon heralds successful excitation of a collective spin-wave mode |W⟩ = (1/√N)Σⱼ|g₁⋯sⱼ⋯gₙ⟩. Entanglement is heralded — detection of a Stokes photon projects two remote ensembles into an entangled Bell state without the photon surviving.

Atomic Frequency Comb

The AFC protocol uses a spectrally shaped comb (spacing Δ, tooth width γ) to achieve deterministic multi-mode storage. Echo time t_s = 1/Δ is programmable. Mode capacity M = Γ_inhom/Δ. A single Er³⁺:Y₂SiO₅ crystal stores M ≈ 10,000 temporal modes simultaneously.

WNSP Connection

Each SNIC node integrates a rare-earth spin-wave memory module. Targets: T₁ ≥ 100 ms, T₂ ≥ 10 ms, M ≥ 10,000 modes, η₀ ≥ 90%, λ = 1550 nm. The memory enables entanglement buffering (T₂ ≫ L/c), temporal multiplexing (M modes), and clock-free synchronisation (t_s = 1/Δ).