CNOT gate implementation using CUDA-Q. The example prepares the Bell state $\lvert\Phi^+\rangle = \frac{1}{\sqrt{2}}(\lvert 00\rangle + \lvert 11\rangle)$.

// Compile: nvq++ main.cpp -o main
// Run:     ./main
 
#include <cudaq.h>
 
struct kernel {
    __qpu__ void operator()() {
        cudaq::qvector<2> q;
        h(q[0]);        // |00> -> |+0>
        cx(q[0], q[1]); // CNOT -> Bell state |Phi+>
        mz(q);
    }
};
 
int main() {
    auto counts = cudaq::sample(kernel{});
    counts.dump();  // ~50% |00>, ~50% |11>
}