def serial_executor(circuit: QPROGRAM, noise: float = BASE_NOISE) -> float:
"""A noisy executor function which executes the input circuit with `noise`
depolarizing noise and returns the expectation value of the ground state
projector. Simulation will be slow for "large circuits" (> a few qubits).
"""
circuit, _ = convert_to_mitiq(circuit)
# Ground state projector.
d = 2**len(circuit.all_qubits())
obs = np.zeros(shape=(d, d), dtype=np.float32)
obs[0, 0] = 1.0
return noisy_simulation(circuit, noise, obs)
def executor(circuit: Circuit) -> float:
"""A one- or two-qubit noisy executor function.
It executes the input circuit with BASE_NOISE depolarizing noise and
returns the expectation value of the ground state projector.
"""
if len(circuit.all_qubits()) == 1:
obs = np.array([[1, 0], [0, 0]])
elif len(circuit.all_qubits()) == 2:
obs = np.array(
[[1, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0], [0, 0, 0, 0]]
)
else:
raise ValueError("The input must be a circuit with 1 or 2 qubits.")
return noisy_simulation(circuit, BASE_NOISE, obs,)
def obs_sim(circ: Circuit) -> float:
# we only want the expectation value not the variance
# this is why we return [0]
return noisy_simulation(circ, noise, obs)
def noisy_backend(circ: Circuit) -> float:
return noisy_simulation(circ, noise, obs)
def executor(qc):
return noisy_simulation(qc, noise=noise, obs=obs)
