Grothendieck inequalities characterize converses to the polynomial method
Abstract
A surprising 'converse to the polynomial method' of Aaronson et al. (CCC'16) shows that any bounded quadratic polynomial can be computed exactly in expectation by a 1-query algorithm up to a universal multiplicative factor related to the famous Grothendieck constant. Here we show that such a result does not generalize to quartic polynomials and 2-query algorithms, even when we allow for additive approximations. We also show that the additive approximation implied by their result is tight for bounded bilinear forms, which gives a new characterization of the Grothendieck constant in terms of 1-query quantum algorithms. Along the way we provide reformulations of the completely bounded norm of a form, and its dual norm.
Keywords
Cite
@article{arxiv.2212.08559,
title = {Grothendieck inequalities characterize converses to the polynomial method},
author = {Jop Briët and Francisco Escudero Gutiérrez and Sander Gribling},
journal= {arXiv preprint arXiv:2212.08559},
year = {2024}
}
Comments
This version adds to the previous one part of the results of an earlier work by the first two authors (arXiv:2204.12303). Accepted in Quantum journal