This quantum circuit simulates the process of Quantum Key Distribution (QKD) for secure communication.
```python
from qiskit import *
# Create circuit with 4 qubits and 4 classical bits
qc = QuantumCircuit(4, 4)
# Alice's bits to send (0 or 1)
alice_bits = [0, 1, 0, 1]
# Alice's choice of bases (0: Z basis, 1: X basis)
alice_bases = [0, 1, 0, 1]
# Bob's choice of bases (0: Z basis, 1: X basis)
bob_bases = [1, 0, 0, 1]
# Alice encodes her bits in the chosen bases
for i in range(4):
# Prepare the qubit in |0⟩ or |1⟩
if alice_bits[i] == 1:
qc.x(i)
# Apply Hadamard if encoding in X basis
if alice_bases[i] == 1:
qc.h(i)
# Bob measures in his chosen bases
for i in range(4):
# Apply Hadamard if measuring in X basis
if bob_bases[i] == 1:
qc.h(i)
# Measure the qubit
qc.measure(i, i)
```'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"}]}\''