Off-diagonal matrix entry
= Off-diagonal matrix entry
{title2=$a_{ij},\quad i\ne j$}
= Off-diagonal matrix element
{synonym}
= Off-diagonal entry
{synonym}
A <matrix entry> whose row and column indices differ. These entries lie outside the <diagonal matrix entries>. A <diagonal matrix> has all its <off-diagonal entries> equal to zero. Cancellation of these entries when averaging <density matrices> does not require the individual preparations to have zero entries there.