Uncertainty relations relative to phase-space quantum reference frames
Miguel Jorquera Riera and Leon Loveridge
Phys. Rev. A 111, L060201 (2025) - Published 9 June, 2025
The authors show that Heisenberg’s uncertainty relation is modified when considered relative to a phase-space quantum reference frame, and that such a frame destroys the incompatibility of position and momentum. They recover the standard uncertainty bound by taking the classical limit of the frame, arguing that standard quantum theory relies on an implicit classical frame.
Effects of superradiance on relativistic Foldy-Wouthuysen densities
F. Daem and A. Matzkin
Phys. Rev. A 111, L060202 (2025) - Published 12 June, 2025
The authors show that the densities in the Foldy-Wouthuysen representation can propagate, in the presence of superradiance, outside the light cone with an arbitrarily high amplitude. These results, obtained in the context of the Klein-Gordon equation, indicate that the Foldy-Wouthuysen densities, despite their attractive properties, might not be fundamentally correct to represent the physical charge densities.
