Mainz 2026 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 57: Open Quantum Systems III

Q 57.5: Talk

Thursday, March 5, 2026, 15:30–15:45, P 4

A witness of superluminal signalling in quantum theory and its modifications. — •Aritro Mukherjee — University of Duisburg-Essen

Linearity of the master equations in quantum theory and in many of its proposed modifications is often taken to guarantee the absence of superluminal signalling, thereby preserving causality. However, in many scenarios, master equations are not always available in a closed analytic form, limiting the applicability of this argument. To address this, we first introduce a general operational witness for detecting superluminal signalling which does not rely on explicit knowledge of a master equation and is easily assessed when analytical methods are not available. Furthermore, applying this witness reveals a surprising result: even linear master equations can permit superluminal signalling unless a specific locality condition is satsfied by the master equations. Hence we show that linearity of the corresponding master equations is not sufficient towards preserving causality. In contrast, the witness we propose provides a necessary and sufficient criterion for ruling out superluminal signalling in full generality. Ref: arXiv:2410.08844 / Phys. Rev. A 112, 062202 (2025)

Keywords: Quantum foundations; Quantum Information; Lindblad evolution; Non-Markovian quantum physics; Modified quantum theory