---
library_name: pytorch
tags:
  - quantum-error-correction
  - circuit-family-classifier
license: other
license_name: nvidia-open-model-license-derivative
---

# QFabric Shield — Family Classifier (per-distance)

Lightweight transformer classifiers that ingest surface-code syndrome history
and emit a softmax over four QFabric circuit families:
`{mps, grover, tebd, emu}`. Used at runtime by the Shield dispatcher to route
syndromes to the correct family-specialized decoder.

One classifier per code distance (input dimension scales with D).

## Architecture

- 4-layer transformer encoder, d_model=128, 4 heads
- ~1M parameters
- Input: `(B, 4, T, D, D)` syndrome tensor
- Output: `(B, 4)` family logits

## Distance variants

Each `d{{N}}/` subdir contains the classifier trained at that distance.