This quantum circuit simulates a phase-flip error on a qubit and corrects it using a phase-flip error correction code.
```python
from qiskit import *
# Create a quantum circuit with 3 qubits and 3 classical bits
qc = QuantumCircuit(3, 3)
# Encode the qubit using a phase-flip error correction code
# Step 1: Apply Hadamard to the data qubit to change basis
qc.h(0)
# Step 2: Encode the qubit using CNOT gates (preparing for phase-flip error correction)
qc.cx(0, 1)
qc.cx(0, 2)
# Introduce a phase-flip error on qubit 1 (simulate error)
qc.z(1)
# Decode the qubits to correct the error
qc.cx(0, 1)
qc.cx(0, 2)
# Step 3: Apply Hadamard to return to the computational basis
qc.h(0)
# Measure all qubits
qc.measure([0, 1, 2], [0, 1, 2])
```
'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"}]}\''