Three-player entangled XOR games are NP-hard to approximate
Abstract
We show that for any eps>0 the problem of finding a factor (2-eps) approximation to the entangled value of a three-player XOR game is NP-hard. Equivalently, the problem of approximating the largest possible quantum violation of a tripartite Bell correlation inequality to within any multiplicative constant is NP-hard. These results are the first constant-factor hardness of approximation results for entangled games or quantum violations of Bell inequalities shown under the sole assumption that P \neq NP. They can be thought of as an extension of Hastad's optimal hardness of approximation results for MAX-E3-LIN2 (JACM'01) to the entangled-player setting. The key technical component of our work is a soundness analysis of a point-vs-plane low-degree test against entangled players. This extends and simplifies the analysis of the multilinearity test by Ito and Vidick (FOCS'12). Our results demonstrate the possibility for efficient reductions between entangled-player games and our techniques may lead to further hardness of approximation results.
Keywords
Cite
@article{arxiv.1302.1242,
title = {Three-player entangled XOR games are NP-hard to approximate},
author = {Thomas Vidick},
journal= {arXiv preprint arXiv:1302.1242},
year = {2020}
}
Comments
The paper has been withdrawn due to an error in the proof of the main theorem. For details, see http://users.cms.caltech.edu/~vidick/errata.pdf