[¦kän·dən ¦shȯrt·lē ¦wig·nər ′fās kən‚ven·shən] (quantum mechanics) Convention relating the phases of states having the same eigenvalue of J2= Jx2+ Jy2+ Jz2, and different eigenvalues of Jz, whereJis the total angular momentum, according to which the matrix elements ofJ+= Jx + iJy andJ-= Jx-iJy between such states are real.