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GHZ State

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The GHZ state, a highly entangeld state entengaling all qubits in a circuit.

\[|GHZ\rangle = \frac{|0\rangle^{\otimes n} + |1\rangle^{\otimes n}}{\sqrt{2}}\]

Create a function that will generate a GHZ state for n qubits. Use the Classiq build in repeat no classical loops. An example circuit is shown below. As you can see to create this circuit, there are two steps:

  1. Apply the H gate to the first qubit.

  2. Perform a CNOT gate between the first qubit and all other qubits, or perform CNOT gates like seen in the image below.

The Classiq library also has a QHZ state preparation build in. That implementation can be found here.

from classiq import *


@qfunc
def main(reg: Output[QArray]):
    allocate(6, reg)
    # your code here
    pass


qprog = synthesize(main)
show(qprog)

Opening: https://platform.classiq.io/circuit/2uFzfHGxMGhCM1qrYeHzjojVohD?version=0.70.0

The full solution for your reference

from classiq import *


@qfunc
def main(reg: Output[QArray]):
    allocate(6, reg)
    H(reg[0])
    repeat(
        count=reg.len - 1,
        iteration=lambda index: CX(ctrl=reg[index], target=reg[index + 1]),
    )


qprog_solution = synthesize(main)
show(qprog_solution)

Opening: https://platform.classiq.io/circuit/2uFzfUVluMz6gBPnnlJhS8lSFKf?version=0.70.0