# Rotation gates (CUDA-Q)
[[r-gate|Rotation gates]] implementation using CUDA-Q. The example applies $R_x(\pi/2)$ to $\lvert 0\rangle$, producing $\frac{1}{\sqrt{2}}(\lvert 0\rangle - i\lvert 1\rangle)$.

```cpp
// Compile: nvq++ main.cpp -o main
// Run:     ./main

#include <cudaq.h>
#include <cmath>

struct kernel {
    __qpu__ void operator()() {
        cudaq::qubit q;
        rx(M_PI / 2.0, q);  // R_x(pi/2) on |0>
        mz(q);
    }
};

int main() {
    auto counts = cudaq::sample(kernel{});
    counts.dump();  // ~50% |0>, ~50% |1>
}
```