to evaluate secretly any two-party computation on private input A and B respectively. Dont repeat everything we have done but use the things we have done and fill in the gaps.
EXTRA POINTS: when solving this question, make sure one party has all his data statistically concealed (whereas the other one is only computationally concealed).
Consider the standard basis S made of and . We know that any pure state of a qubit can be expressed as a+b where a and b are complex numbers such that ||a||2+||b||2 = 1. Thus any element is specified by a pair (a,b) so that corresponds to (1,0) and to (1,0). We have also seen that the diagonal basis D made of is conjugate to the standard basis which means that if we measure or according to basis D the probabilities of each outcome are exactly 1/2.
- Find yet a third basis C that is conjugate to both bases S and D.
- Find a basis B=[(u,v),(x,y)] such that measuring according to B maximizes the prediction probability for elements of bases S,D,C. More precisely, find a basis and a strategy that will have the highest success probability of issuing the correct answer when a random element of either S,D or C is given and that the basis is revealed after the measurement has been done.