Symmetry is among the most fundamental and powerful concepts in nature, whose existence is usually taken as given, without explanation. We explore whether symmetry can be derived from more fundamental principles from the perspective of quantum information. Starting with a two-qubit system, we show there are only two minimally entangling logic gates: the identity and the , which interchanges the two states of the qubits. We further demonstrate that, when viewed as an entanglement operator in the spin-space, the -matrix in the two-body scattering of fermions in the -wave channel is uniquely determined by unitarity and rotational invariance to be a linear combination of the identity and the . Realizing a minimally entangling -matrix would give rise to global symmetries, as exemplified in Wigner’s spin-flavor symmetry and Schrödinger’s conformal invariance in low energy quantum chromodynamics. For species of qubit, the identity gate is associated with an symmetry, which is enlarged to when there is a species-universal coupling constant.
ASJC Scopus subject areas
- Physics and Astronomy (miscellaneous)