References
The main implementation is in
https://github.com/pytorch/pytorch/tree/master/aten/src/ATen/native/quantized
- Introducing Quantized Tensor - https://github.com/pytorch/pytorch/wiki/Introducing-Quantized-Tensor 
- Model Quantization for PyTorch (Proposal) #18318 
- torch_quantization_design_proposal - https://github.com/pytorch/pytorch/wiki/torch_quantization_design_proposal 
Links
- https://github.com/pytorch/pytorch/blob/master/test/quantization/core/test_quantized_tensor.py 
- https://github.com/pytorch/pytorch/blob/master/aten/src/ATen/test/quantized_test.cpp 
- https://github.com/pytorch/pytorch/blob/master/aten/src/ATen/native/quantized/README.md 
- https://pytorch.org/blog/introduction-to-quantization-on-pytorch/ 
- Deep Dive on PyTorch Quantization - Chris Gottbrath