A quantum circuit that initializes eight qubits to the |+⟩ state, applies controlled-Z gates to form an 'H' shaped cluster state, and measures all qubits.
```python
from qiskit import QuantumCircuit
# Create a circuit that initializes eight qubits to the |+⟩ state,
# applies controlled-Z gates in the shape of an 'H', and then measures all qubits.
qc = QuantumCircuit(8, 8)
# Initialize all qubits to |+> state
qc.h(range(8))
# Apply CZ gates to form an 'H' shaped cluster state
# Left vertical line of 'H'
qc.cz(0, 1)
qc.cz(1, 2)
# Right vertical line of 'H'
qc.cz(5, 6)
qc.cz(6, 7)
# Horizontal connector of 'H'
qc.cz(2, 3)
qc.cz(3, 4)
qc.cz(4, 5)
# Measure all qubits
qc.measure(range(8), range(8))
```'Failed to run program: \'409 Client Error: Conflict for url: https://api.quantum.ibm.com/runtime/jobs. {"errors":[{"message":"You have reached the limit of 3 pending jobs. Please wait for a job to complete or cancel one before submitting anything new.","code":3458,"solution":"Wait until some previous jobs were finished. You can cancel pending jobs to run new jobs.","more_info":"https://docs.quantum-computing.ibm.com/errors"}]}\''