Time-reversal symmetry (TRS) of electrons is associated with an anti-unitary operator with T 2 = − 1 . which induces Kramers degeneracy and plays an important role in realizing the quantum spin Hall effect (QSHE). By contrast. TRS of photons is described by T b 2 = 1 . https://jalyttlers.shop/product-category/pheasant-oak-serving-board/