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arXiv · 2511.06624

No-signalling-projection-invariant Bell inequalities

Soumyadip Patra·Jitendra Prakash·Aaditya Paudel·Peter Bierhorst
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Abstract

In this paper, we highlight how any Bell inequality for a configuration involving $n$ parties each performing one of $m$ binary-outcome measurements has a canonical form that is no-signalling-projection invariant. Specifically, the $L^2$-projection of weakly signalling data onto the no-signalling polytope leaves the violation of this canonical Bell inequality unchanged. Our methods allow us to derive a general closed formula for the projection and present a substantially more computationally simple procedure for its evaluation. We also show this can be generalised to non-standard projections of potential interest for certain applications. No-signalling projections serve as a preliminary step before undertaking any device-independent application involving Bell experiment data, such as hypothesis testing against local realism, random number generation and entanglement detection.

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Soumyadip Patra, Jitendra Prakash, Aaditya Paudel, Peter Bierhorst. 2025-11-10. No-signalling-projection-invariant Bell inequalities. https://arxiv.org/abs/2511.06624

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