A theoretical arXiv preprint says a proposed extension of quantum correlations called jamming has no consistent middle ground under its assumptions: if the jamming maps must be positive for every input, they reduce to identity maps and return ordinary quantum behavior; if jamming is allowed to depend on the quantum state, it is incompatible with ensemble equivalence and no-superluminal signaling for all preparations.
The paper’s broader relativistically causal quantum set, RCQ, is nevertheless a strict extension of the usual quantum set when jamming is allowed. In plain terms, its rules admit correlations that ordinary quantum theory does not, but the paper’s no-go results say those extra correlations cannot form the intermediate quantum theory being tested.
Posted on arXiv as version 1 on 20 August 2026, the work is a formal modeling study. It examines a tripartite Bell behavior—a mathematical description of settings and outcomes for three spacelike-separated parties, Alice, Bob and Charlie—and extends an operator framework to characterize correlations compatible with relativistic causality.
The larger set, and the catch
In the specified geometry, “jamming” means that Bob’s setting can change the joint Alice-Charlie correlation while the overall behavior retains the stated relativistic-causality structure. The authors give an if-and-only-if operator representation for such tripartite behaviors, making the representation both necessary and sufficient.
The first no-go result concerns jamming maps that are positive on every input, a condition that preserves positivity in the model. The maps are then forced to be identity maps, so the construction reduces to standard quantum behaviors.
The second result concerns state-dependent jamming. Under ensemble equivalence—the idea that different descriptions of the same statistical mixture should produce the same operational results—the extension cannot also satisfy no-superluminal signaling for every preparation.
The paper therefore identifies ordinary quantum theory without jamming and a fully post-quantum relativistically causal theory based on arbitrary Hermitian operators as the remaining consistent possibilities.
A warning for cryptography
The paper then constructs attacks on specified device-independent bit-commitment and secret-sharing models. In the multi-prover bit-commitment construction, the combined opening success is at least 2 − 2ε − 2δ and approaches 2 as the hiding and soundness errors ε and δ tend to zero.
In the specified secret-sharing geometry, the explicit RC behavior reaches S = 8, the algebraic maximum of the Svetlichny expression, while a dishonest Alice has Pguess = 1—perfect secret guessing.
Together, the constructions support the paper’s conclusion that input-output statistics alone are insufficient for the stated relativistic-security goal. A security specification must also include where the measurement events occur in spacetime, at least for the adversaries and geometries modeled here.
A result about models, not observed signals
These are formal results, not observations of faster-than-light communication. The analysis uses operator representations, proofs and explicitly constructed behaviors; its conclusions are conditional on the specified jamming geometries and axioms, and the RCQ analysis is restricted to finite-dimensional local Hilbert spaces. It does not claim that every device-independent cryptographic primitive is insecure.
Paper data and sources
Original title: Jamming Extensions of Quantum Correlations Lead to Hidden Superluminal Signaling
Authors: Ravishankar Ramanathan, Xie Sicheng, Michał Eckstein, Paweł Horodecki
Journal/Repository: arXiv
Status: Preprint, not yet peer-reviewed
First online: 2026-08-20
DOI: Not available
Original paper · Full text