Quantum Computing, Qiskit, General U3 Gate, Controlled U3 Gate, Tutorial.
the value of λ can be anything. It doesn’t have any impact on the final state. Implementing the circuit with calculated θ and 𝜙 values: Executing and visualizing the circuit to find out the final state: The statevector shows two complex values where the value is 0.5 for |0⟩ (with 0 imaginary part)