# 📐 L2 Spec — Entangled-Photon Microscopy (N00N / SPDC imaging) Mismatch-Only Spec
**ID:** `L2-155-001` · **Status:** ⊙ Testnet (genesis catalog)
**Parents:** ⬆ Principle [`L1-155`](/artifact/l1/L1-155)
> **🎯 Tolerance (ε):** expression
> **⚖ Difficulty score:** 0.55 · **Delta tier:** 5
> **⛓ On-chain block:** 41554245
---
## 1. Domain Ω
**Type:** `range`
| Parameter | Unit | Range |
|---|---|---|
| H | px | 64 |
| W | px | 64 |
| N photons | photons | 2 – 10 |
| Photon loss | — | 0.0 – 0.9 |
| N coincidences | — | 1000 – 100000000 |
| Phase instability | — | 0.0 – 0.5 |
| Detector dark counts | — | 0.0 – 1.0 |
| Mode coupling efficiency | — | 0.1 – 1.0 |
## 2. Tolerance (ε)
**Type:** `fn`
```
8.0 + 2.5 * log10(N_coincidences / 1000) - 10.0 * photon_loss + 5.0 * mode_coupling_efficiency - 6.0 * phase_instability
```
## 3. Difficulty
| Property | Value |
|---|---|
| Difficulty score | 0.55 |
| Delta tier | 5 |
## 4. Fingerprint
`0bebd80708d69ef02d9396b9f4fbc958ac0e4cd80fe58ce4a8a8da782c072522`
## 5. On-chain Registration
- **Chain hash:** `0x486d27851bd316826c41592abc382d5541b32b8b569b5d14b4ad18f5ca37a3b1`
- **Chain tx hash:** `0xcd2bde7b46ccff4b19aea68ebf6b65299d4869d4deefc6012f5acf9345ec0194`
- **Chain block:** `41554245`
---
## File Mapping
This bundle consists of: `L2-155-001.md`, `L2-155-001.json`.
| File | Role | How to regenerate |
|------|------|-------------------|
| `L2-155-001.md` | Source of truth — edit this | Human or LLM |
| `L2-155-001.json` | Structured metadata for the registry | LLM regenerates from the sections above |
**Prompt for your LLM after editing this Markdown:**
> Read the attached Markdown. Regenerate the sibling `.json` so every field matches.
> Preserve the schema documented in the rows above.
> Output each file in its own fenced code block tagged with the filename.
> Output only the JSON object.
_This Markdown was auto-synthesized from the catalog row for `L2-155-001`._
_Edit it, regenerate the JSON, and submit at [/submit](/submit) to claim the artifact._