[diegoperini]

Yes, the constraints reduce the capacity from the ideal limit of 4 real numbers.

(a + bi) type of complex numbers are indistinguishable from (b + ai) ones. Deciding the value of b immediately reduces the number of possible values for a to 2, which is a and -a respectively. Luckily, the real number line is continuous. We can accept such sacrifices without too much precision loss.

Also I should note that my calculations assumed a pair of maximally entangled particles per quantum circuit element since that's the most straightforward way to harvest quantum information with minimum number of objects.