Two quantum particles can be described by one joint amplitude table. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

A pair has one joint amplitude table

The nonzero joint amplitudes sit on the zero-zero and one-one same-outcome cells. Each has probability 1/2.

Psame cells=12P_{\text{same cells}}=\frac{1}{2}
Joint state tableThe table is one two-particle quantum state.001/sqrt(2)P=1/2010P=0100P=0111/sqrt(2)P=1/2det = 1/2not product

Only the same-outcome cells are populated

The joint table is read cell by cell before any single correlation sentence is made.

cellProlezero-zero12samezero-one0mixedone-one12same\begin{array}{c|c|c}\text{cell}&P&\text{role}\\\text{zero-zero}&\frac{1}{2}&\text{same}\\\text{zero-one}&0&\text{mixed}\\\text{one-one}&\frac{1}{2}&\text{same}\\\end{array}
Joint-cell scanThe nonzero cells are exactly the same-outcome cells.001/sqrt(2)P=1/2010P=0100P=0111/sqrt(2)P=1/2det = 1/2not product

The mixed cells have zero probability

The zero-one and one-zero mixed cells have probability 0 in this basis.

Pmixed cells=0P_{\text{mixed cells}}=0
Joint probabilitiesEvery displayed probability is squared from an amplitude.001/sqrt(2)P=1/2010P=0100P=0111/sqrt(2)P=1/2det = 1/2not product