A Bell correlation strength three-row scan holds same-bit correlation fixed at probability one while the split between the zero-zero and one-one branches moves toward even, so the checked determinant grows from row to row. The three rows split twelve-thirteenths and five-thirteenths (determinant 60/169), four-fifths and three-fifths (determinant 12/25), and the even split at one over square root of two on each branch (determinant 1/2, the maximal case already checked in chapter five) for the stated toy two-qubit ledger; real entangled-qubit pairs have finite gate fidelity, decoherence, and readout crosstalk that erode the same-bit correlation over time.

Three correlated two-qubit splits keep same-bit correlation while the checked determinant grows toward the maximal even split. Exact arithmetic here means exact results for the stated model inputs; measured inputs still carry uncertainty and significant-figure limits.

highlighted = computed this step

An uneven split still gives same-bit correlation

The weakest row splits twelve-thirteenths and five-thirteenths between the zero-zero and one-one branches. Same-bit outcomes still have probability one; the split only changes how much weight each branch carries.

P00=144169,P11=25169P_{00}=\frac{144}{169},\quad P_{11}=\frac{25}{169}
Uneven correlated splitThe weakest determinant row renders here.0012/13P=144/169010P=0100P=0115/13P=25/169det = 60/169not product

The determinant grows as the split becomes even

Three rows keep same-bit correlation while the split moves toward even. The determinant, computed from the two nonzero diagonal amplitudes, grows from row to row and is largest exactly at the even split from chapter five.

a00a11det⁡12135136016945351225121212\begin{array}{c|c|c}a_{00}&a_{11}&\det\\\frac{12}{13}&\frac{5}{13}&\frac{60}{169}\\\frac{4}{5}&\frac{3}{5}&\frac{12}{25}\\\frac{1}{\sqrt{2}}&\frac{1}{\sqrt{2}}&\frac{1}{2}\end{array}
Middle correlated splitThe middle row's determinant sits between the other two.004/5P=16/25010P=0100P=0113/5P=9/25det = 12/25not product

The even split reaches the maximal checked determinant

The third row is the Bell pair already checked in chapter five: an even split at one over square root of two on each branch, giving the largest determinant of the three rows.

det⁡max⁡=12\det_{\max}=\frac{1}{2}
Even correlated splitThe third row is the maximal-determinant case.001/sqrt(2)P=1/2010P=0100P=0111/sqrt(2)P=1/2det = 1/2not product