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Factoring Non-negative Operator Valued Trigonometric Polynomials in Two Variables

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arxiv 1811.06005 v4 pith:D2UUFGWS submitted 2018-11-14 math.FA

Factoring Non-negative Operator Valued Trigonometric Polynomials in Two Variables

classification math.FA
keywords finitenon-negativeoperatorpolynomialstrigonometricvaluedvariablesanalytic
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It is shown using Schur complement techniques that on finite dimensional Hilbert spaces, a non-negative operator valued trigonometric polynomial in two variables with degree $(d_1,d_2)$ can be written as a finite sum of hermitian squares of at most $2d_2$ analytic polynomials.

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Cited by 2 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. No finite level of the NPA hierarchy is exact for the doubly-tilted CHSH functional near the critical tilt

    quant-ph 2026-07 conditional novelty 8.0

    No finite NPA level reproduces the quantum value of the doubly-tilted CHSH functional in any neighbourhood of the critical tilt; each level strictly overshoots with at least quadratic gap.

  2. A phase transition in the exactness of the NPA hierarchy at the critical doubly-tilted CHSH functional

    quant-ph 2026-07 conditional novelty 7.0

    For the doubly-tilted CHSH functional, the NPA hierarchy is exact at every level above the critical tilt and provably non-exact near it, a phase transition in exactness.