Infinitesimal reference frames suffice to determine the asymmetry properties of a quantum system

Understand

Symmetry principles are fundamental in physics, and while they are well understood within Lagrangian mechanics, their impact on quantum channels has a range of open questions.

• The theory of asymmetry grew out of information-theoretic work on entanglement and quantum reference frames, and allows us to quantify the degree to which a quantum system encodes coordinates of a symmetry group.
• Recently, a complete set of entropic conditions was found for asymmetry in terms of correlations relative to infinitely many quantum reference frames.
• However, these conditions are difficult to use in practice and their physical implications unclear.