Quantize by Drift: label-free mixed-precision quantization for text embedders hits 0.911 Spearman

_reachsumit · x · 2026-10-08

A new paper introduces Quantize by Drift, a label-free mixed-precision post-training quantization method for text embedders. Instead of relevance labels, it measures quantization-induced representation drift: quantize one module, re-encode the corpus, and record how far output embeddings move from full-precision positions. Across five embedders, configuration-level drift orders mixed-precision plans against held-out retrieval quality at macro Spearman 0.911, transports across corpora and domains, and requires one additive allocation under a packed-byte budget with no labels or search. Pre-registered checks hold 3/3, though drift is numerically below same-budget uniform precision at the main budget.

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