We study semiclassical communication in positivity-violating $k$-essence scalar field theories, with superluminal modes propagating on a rolling background. The self-interactions due to the nonlinear nature of these theories pose a constraint on the rate of superluminal information transfer. We derive a novel bit rate bound on superluminal communication within a conceptual model, to which a general class of $k$-essence theories reduces. Our result implies the possibility that, even if these positivity-violating $k$-essence theories may not possess a maximal information propagation speed, there is nevertheless an upper bound on the rate of information transfer.

• Received 13 January 2021
• Accepted 16 September 2021

DOI:https://doi.org/10.1103/PhysRevD.104.084062

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Published by the American Physical Society