def test_simulator() -> None:
b = BraketBackend(
s3_bucket=S3_BUCKET,
s3_folder=S3_FOLDER,
device_type="quantum-simulator",
provider="amazon",
device="sv1",
)
assert b.supports_shots
c = Circuit(2).H(0).CX(0, 1)
b.compile_circuit(c)
n_shots = 100
h0, h1 = b.process_circuits([c, c], n_shots)
res0 = b.get_result(h0)
readouts = res0.get_shots()
assert all(readouts[i][0] == readouts[i][1] for i in range(n_shots))
res1 = b.get_result(h1)
counts = res1.get_counts()
assert len(counts) <= 2
assert sum(counts.values()) == n_shots
zi = QubitPauliString(Qubit(0), Pauli.Z)
assert b.get_pauli_expectation_value(
c, zi, poll_timeout_seconds=60, poll_interval_seconds=1
) == pytest.approx(0)
# Circuit with unused qubits
c = Circuit(3).H(1).CX(1, 2)
b.compile_circuit(c)
h = b.process_circuit(c, 1)
res = b.get_result(h)
readout = res.get_shots()[0]
assert readout[1] == readout[2]
def test_moments_with_shots() -> None:
b = BraketBackend(local=True)
c = Circuit(1).H(0)
z = QubitPauliString(Qubit(0), Pauli.Z)
e = b.get_pauli_expectation_value(c, z, n_shots=10)
assert abs(e) <= 1
v = b.get_pauli_variance(c, z, n_shots=10)
assert v <= 1
op = QubitPauliOperator({z: 3})
e = b.get_operator_expectation_value(c, op, n_shots=10)
assert abs(e) <= 3
v = b.get_operator_variance(c, op, n_shots=10)
assert v <= 9
def test_variance() -> None:
b = BraketBackend(local=True)
assert b.supports_variance
# - Prepare a state (1/sqrt(2), 1/sqrt(2)).
# - Measure w.r.t. the operator Z which has evcs (1,0) (evl=+1) and (0,1) (evl=-1).
# - Get +1 with prob. 1/2 and -1 with prob. 1/2.
c = Circuit(1).H(0)
z = QubitPauliString(Qubit(0), Pauli.Z)
assert b.get_pauli_expectation_value(c, z) == pytest.approx(0)
assert b.get_pauli_variance(c, z) == pytest.approx(1)
op = QubitPauliOperator({z: 3})
assert b.get_operator_expectation_value(c, op) == pytest.approx(0)
assert b.get_operator_variance(c, op) == pytest.approx(9)