Results · The price of perfection

An explicit nonlocal game of quantum value one that needs exponential entanglement

In plain wordsA specific game that quantum players can win with probability as close to one as they like, but every step closer needs an exponentially larger quantum system; earlier explicit games forced only a polynomial cost.

The result

As the paper states it, in briefA binary linear system game with 1687 equations in 1993 variables, of quantum value one, in which winning with probability 1−ε needs entanglement entropy ε−1+o(1), hence local dimension exp⁡(ε−1+o(1)); the exponent is sharp.

Questionson the index

How this was checked

Independent computation
Exact certificates for the four computational statements, each re-checked by a separately written program in anc/.
In Lean
Theorem A (conditional on the published perfect tensor-strategy implication) and Theorems C, D, E and F checked in Lean 4, standard axioms only; independent fresh build and two kernel replays of the release.
Lean
Theorem A, conditional on the published implication from perfect tensor-product strategies, and Theorems C, D, E and F formalized in Lean 4; the release was rebuilt from scratch and replayed by Lean's checker and the independent nanoda checker. Source and recorded axioms in the repository. Lean source
Peer review
Not yet.

Every check here is internal. How we check results.

Label checked .

Novelty and credit

Novelty
New. For explicit games of quantum value one, the best previous lower bound was polynomial in 1/ε. The same tools give sharp rates for the CHSH(n) games and the game of Slofstra and Vidick.

Versionstwo, each with its own DOI

Every archived version, newest first. Dates are Zenodo publication dates. All versions: 10.5281/zenodo.23697254, which always resolves to the newest.
VersionDateDOINotes
1.1.010.5281/zenodo.23878232Adds a formal verification in Lean 4: Theorem A, conditional on the published implication from perfect tensor-product strategies, and Theorems C, D, E and F, with only the standard axioms. The release was rebuilt from scratch and replayed by two independent kernel checkers. The mathematics is unchanged. PDF hosted here.
1.0.010.5281/zenodo.23697255

Paper, code and links

PDF

papers/explicit-game-v1.1.0.pdf, version 1.1.0, 1,246,081 bytes, 93 pages.

SHA-256 9b7793fe0474706173d8e3c25d4d5174cc4eca6d1dc5251e97583c42288fd8fc

Corrections

None so far.

All corrections, and what counts as one.

Cite

@misc{mghirbi2026explicitgame,
  author  = {Mghirbi, Nidhal and Douglas, Seth},
  title   = {An explicit nonlocal game of quantum value one that needs exponential entanglement},
  year    = {2026},
  version = {1.1.0},
  doi     = {10.5281/zenodo.23878232},
  url     = {https://doi.org/10.5281/zenodo.23878232}
}

explicit-game.bibAll papers as BibTeX