Challenge C1

Generate GHZ state

Your task is to create Greenberger–Horne–Zeilinger (GHZ) state on N qubits (1 ≤ N ≤ 8) in zero |0..0⟩ state.

The GHZ state is defined as |GHZ⟩ = 1/√2 (|0..0⟩ + |1..1⟩).

You have to implement an operation which takes an array of N qubits and you need to create the GHZ state on them. The operation should have the following signature: