Function getRandomKrausMap

tests/utils/random.cpp:405–431

vector<qmatrix> getRandomKrausMap(int numQb, int numOps) {
    DEMAND( numOps >= 1 );

    // generate random unitaries
    vector<qmatrix> ops(numOps);
    for (auto& u : ops)
        u = getRandomUnitary(numQb);

    // generate random weights
    vector<qreal> weights(numOps);
    for (auto& w : weights)
        w = getRandomReal(0, 1);
        
    // normalise random weights
    qreal sum = 0;
    for (auto& w : weights)
        sum += w;
    for (auto& w : weights)
        w = std::sqrt(w/sum);
        
    // normalise unitaries according to weights
    for (int i=0; i<numOps; i++)
        ops[i] *= weights[i];

    DEMAND( isApproxCPTP(ops) );
    return ops;
}