Add quantization (PTQ) docs for super3

docs/nemotron/super3/README.md

@@ -64,6 +64,7 @@ $ uv run nemotron super3 sft --run YOUR-CLUSTER
 |-------|------|---------|-------|
 | 0 | [Pretraining](./pretrain.md) | Base model training with MoE and multi-token prediction | [pretrain.md](./pretrain.md) |
 | 1 | [SFT](./sft.md) | Multi-domain instruction tuning | [sft.md](./sft.md) |
+| — | [Quantization](./quantization.md) | Post-training quantization (FP8 / NVFP4) | [quantization.md](./quantization.md) |
 
 ## Model Specifications
 
@@ -164,6 +165,7 @@ wandb login
 
 - [Stage 0: Pretraining](./pretrain.md)
 - [Stage 1: SFT](./sft.md)
+- [Quantization (PTQ)](./quantization.md)
 - [Artifact Lineage](../../nemo_runspec/artifacts.md)
 - [Execution through NeMo-Run](../../nemo_runspec/nemo-run.md)
 - [W&B Integration](../wandb.md)

docs/nemotron/super3/quantization.md

@@ -0,0 +1,112 @@
+# Quantization (PTQ)
+
+This stage quantizes the pretrained Nemotron 3 Super model using [Megatron-Bridge](../nvidia-stack.md#megatron-bridge)'s post-training quantization (PTQ) pipeline.
+
+---
+
+## Quantization Configurations
+
+Nemotron 3 Super supports four quantization configurations tailored for the Mamba-MoE architecture:
+
+| Config Name | Format | Description |
+|---|---|---|
+| `mamba_moe_fp8_aggressive` | FP8 | Aggressive FP8 quantization for Mamba-MoE |
+| `mamba_moe_fp8_conservative` | FP8 | Conservative FP8 quantization for Mamba-MoE |
+| `mamba_moe_nvfp4_aggressive` | NVFP4 | Aggressive NVFP4 quantization for Mamba-MoE |
+| `mamba_moe_nvfp4_conservative` | NVFP4 | Conservative NVFP4 quantization for Mamba-MoE |
+
+Pass the desired config name via `--export-quant-cfg` to `quantize.py`.
+
+---
+
+## Recipe Execution
+
+### Direct Script Execution (Megatron-Bridge)
+
+For direct execution outside this CLI, use the scripts in the [Megatron-Bridge](https://github.com/NVIDIA-NeMo/Megatron-Bridge) repository:
+
+```bash
+# Clone the repository and checkout the super-v3 branch
+git clone https://github.com/NVIDIA-NeMo/Megatron-Bridge.git
+cd Megatron-Bridge
+git checkout super-v3
+```
+
+### Quantize
+
+```bash
+export HF_MODEL=/path/to/hf/model
+export MEGATRON_SAVE_PATH=/path/to/quantized/megatron/ckpt
+
+torchrun --nproc_per_node=16 examples/quantization/quantize.py \
+    --hf-model-id $HF_MODEL \
+    --export-quant-cfg mamba_moe_nvfp4_conservative \
+    --megatron-save-path $MEGATRON_SAVE_PATH \
+    --pp 2 \
+    --tp 8 \
+    --ep 8 \
+    --trust-remote-code
+```
+
+### Resume Quantized Megatron Checkpoint and Generate
+
+```bash
+torchrun --nproc_per_node=16 examples/quantization/ptq_generate.py \
+    --hf-model-id $HF_MODEL \
+    --megatron-load-path $MEGATRON_SAVE_PATH \
+    --pp 2 \
+    --tp 8 \
+    --ep 8 \
+    --trust-remote-code
+```
+
+### Export Quantized Megatron Checkpoint to Huggingface Checkpoint
+
+After quantization, export the Megatron checkpoint back to Hugging Face format:
+
+```bash
+export EXPORT_DIR=/path/to/output/hf/ckpt
+
+torchrun --nproc_per_node=16 examples/quantization/export.py \
+    --hf-model-id $HF_MODEL \
+    --megatron-load-path $MEGATRON_SAVE_PATH \
+    --export-dir $EXPORT_DIR \
+    --pp 8 \
+    --dtype bfloat16 \
+    --trust-remote-code
+```
+
+Notes:
+- For multi-node setups (e.g. 2 nodes with 8× H100), increase `--pp` accordingly (e.g. `--pp 2`) and use a job scheduler like SLURM to launch across nodes.
+
+---
+
+## Infrastructure
+
+This stage uses the following components from the [NVIDIA AI Stack](../nvidia-stack.md):
+
+| Component | Role | Documentation |
+|-----------|------|---------------|
+| [Megatron-Core](../nvidia-stack.md#megatron-core) | Distributed training primitives (TP, PP, EP) | [GitHub](https://github.com/NVIDIA/Megatron-LM) |
+| [Megatron-Bridge](../nvidia-stack.md#megatron-bridge) | PTQ quantization, checkpoint export | [Docs](https://docs.nvidia.com/nemo/megatron-bridge/latest/) |
+| [Model-Optimizer](https://github.com/NVIDIA/TensorRT-Model-Optimizer) | Quantization algorithms (FP8, NVFP4) | [GitHub](https://github.com/NVIDIA/TensorRT-Model-Optimizer) |
+
+### Parallelism Configuration
+
+| Parallelism | Default | Flag |
+|-------------|---------|------|
+| Tensor (TP) | 8 | `--tp` |
+| Pipeline (PP) | 2 | `--pp` |
+| Expert (EP) | 8 | `--ep` |
+
+**Minimum resources:** 2 nodes with 8× H100 GPUs.
+
+---
+
+## Reference
+
+- [Megatron-Bridge Nemotron 3 Super](https://github.com/NVIDIA-NeMo/Megatron-Bridge/blob/super-v3/docs/models/llm/nemotron3-super.md) — MB documentation and examples
+- [NVIDIA AI Stack](../nvidia-stack.md) — Megatron-Core, Megatron-Bridge documentation
+- [Stage 0: Pretraining](./pretrain.md) — Pretrain the base model
+- [Stage 1: SFT](./sft.md) — Supervised fine-tuning
+- [Back to Overview](./README.md)