PolarQuant: Optimal Gaussian Weight Quantization via Hadamard Rotation for LLM Compression
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Abstract (arXiv)
We present PolarQuant, a post-training weight quantization method for large language models (LLMs) that exploits the distributional structure of neural network weights to achieve near-lossless compression. PolarQuant operates in three stages: (1) block-wise normalization to the unit hypersphere, (2) Walsh-Hadamard rotation to transform coordinates into approximately Gaussian random variables, and (3) quantization with centroids matched to the Gaussian distribution. Our ablation reveals that Hadamard rotation alone accounts for 98% of the quality improvement, reducing Qwen3.5-9B perplexity from 6.90 (absmax Q5) to 6.40 (Delta = +0.03 from FP16), making it practically lossless without any calibration data. Furthermore, PolarQuant functions as an effective preprocessing step for downstream INT4 quantizers: PolarQuant Q5 dequantized and re-quantized by torchao INT4 achieves perplexity 6.56 versus 6.68 for direct absmax INT4, while maintaining 43.1 tok/s throughput at 6.5 GB VRAM. Code and models are publicly available.
Key facts. Cited by 2 papers in the map (data through 14 Oct 2026). Builds on 8 of its 18 references that are in the map. First posted on arXiv 30 Mar 2026.
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8 of 18 references.
References · 8
- 2016Pointer Sentinel Mixture Modelscited by 3,096
- 2022GPTQ: Accurate Post-Training Quantization for Generative Pre-trained Transformerscited by 1,919
- 2017Quantization and Training of Neural Networks for Efficient Integer-Arithmetic-Only Inferencecited by 1,593
- 2023AWQ: Activation-aware Weight Quantization for LLM Compression and Accelerationcited by 1,298
- 2024QuaRot: Outlier-Free 4-Bit Inference in Rotated LLMscited by 634
- 2024SpinQuant: LLM quantization with learned rotationscited by 471
- 2023QuIP: 2-Bit Quantization of Large Language Models With Guaranteescited by 414
- 2025TurboQuant: Online Vector Quantization with Near-optimal Distortion Ratecited by 125
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Citing papers per year: 2026: 2.
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- 2024CDQuant: Greedy Coordinate Descent for Accurate LLM Quantization
- 2025PolarQuant: Quantizing KV Caches with Polar Transformation
- 2026TWLA: Achieving Ternary Weights and Low-Bit Activations for LLMs via Post-Training Quantization
- 2026NanoQuant: Efficient Sub-1-Bit Quantization of Large Language Models
- 2023FineQuant: Unlocking Efficiency with Fine-Grained Weight-Only Quantization for LLMs
- 2026ThinQuant: Scalable Rotation Learning for Weight and Activation Quantization of LLMs
- 2024CrossQuant: A Post-Training Quantization Method with Smaller Quantization Kernel for Precise Large Language Model Compression
- 2022SmoothQuant: Accurate and Efficient Post-Training Quantization for Large Language Models