This circuit creates a superposition, entangles two qubits, erases which-path information, and then measures the qubits.
```python
from qiskit import QuantumCircuit
# Create a quantum circuit with 2 qubits and 2 classical bits
qc = QuantumCircuit(2, 2)
# Create a superposition on qubit 0
qc.h(0)
# Entangle qubit 0 and qubit 1, encoding which-path information in qubit 1
qc.cx(0, 1)
# Apply Hadamard gate to qubit 1 to erase which-path information
qc.h(1)
# Measure both qubits
qc.measure([0, 1], [0, 1])
```'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"}]}\''