Improved Two-source Extractors against Quantum Side Information

Two-source extractors aim to extract randomness from two independent sources of weak randomness. It has been shown that any two-source extractor which is secure against classical side information remains secure against quantum side information. Unfortunately, this generic reduction comes with a significant penalty to the performance of the extractor. In this paper, we show that the two-source extractor from Dodis et al. performs equally well against quantum side information as in the classical realm, surpassing previously known results about this extractor. Additionally, we derive a new quantum XOR-Lemma which allows us to re-derive the generic reduction but also allows for improvements for a large class of extractors.

@article{miller2025_2503.05528,
  title={ Improved Two-source Extractors against Quantum Side Information },
  author={ Jakob Miller and Martin Sandfuchs and Carla Ferradini },
  journal={arXiv preprint arXiv:2503.05528},
  year={ 2025 }
}