from qutip_qip.circuit import QubitCircuit
from qutip_qip.algorithms import BitFlipCode, PhaseFlipCode
[docs]
class ShorCode:
"""
Constructs the 9-qubit Shor code encoding circuit using BitFlipCode and PhaseFlipCode.
The Shor code protects against arbitrary single-qubit errors by combining
bit-flip and phase-flip redundancy encoding.
"""
def __init__(self):
self.n_qubits = 9 # Total qubits in the Shor code
[docs]
def encode_circuit(self) -> QubitCircuit:
"""
Construct the 9-qubit Shor code encoding circuit.
Returns
-------
qc : :class:`.QubitCircuit`
Circuit that encodes one logical qubit into the Shor code.
"""
qc = QubitCircuit(num_qubits=self.n_qubits)
# Step 1: Bit-flip encode qubit 0 → [0, 1, 2]
bit_code = BitFlipCode()
bit_qc = bit_code.encode_circuit([0, 1, 2])
qc.add_circuit(bit_qc)
# Step 2: Phase-flip encode each of [0,1,2] across 3 qubits each:
phase_blocks = [[0, 3, 6], [1, 4, 7], [2, 5, 8]]
for block in phase_blocks:
phase_code = PhaseFlipCode()
phase_qc = phase_code.encode_circuit(block)
qc.add_circuit(phase_qc)
return qc