# How can I convert the unitary matrix $e^\frac{i\pi}{2}$ into a quantum circuit in Qiskit?

How can I put the unitary matrix $$e^\frac{i\pi}{2}I$$ to the quantum circuit?

I don't know if it is belong to $$U3(\theta, \phi, \lambda), U2(\phi, \lambda), U1(\lambda)$$

Thanks a lot.

$$I$$ is the identity matrix. In a quantum circuit, it means "do nothing". You don't need to program it in. The global phase doesn't make a difference to this either.

• FWIW you can add global phases in Qiskit, circuit = QuantumCircuit(1); circuit.global_phase = pi/2 – Cryoris Sep 16 '20 at 15:25
• Thanks a lot, I know sth! – Physics World Sep 16 '20 at 17:36
• $e^\frac{i\pi}{2}=i$, so it rotates the phase by 90${}^\circ$. – peterh Sep 17 '20 at 15:50