def test_imperfect_code():
# Also known as the bit-flip code.
bit_flip_code = sc.StabilizerCode(group_generators=['ZZI', 'ZIZ'],
correctable_errors=['X'])
for input_val in [0, 1]:
_, traced_out_state_no_error = encode_corrupt_correct(bit_flip_code,
input_val,
error_gate=None,
error_loc=None)
for error_gate in [cirq.X]:
for error_loc in range(bit_flip_code.n):
decoded, traced_out_state = encode_corrupt_correct(
bit_flip_code, input_val, error_gate, error_loc)
assert decoded == input_val
np.testing.assert_allclose(traced_out_state_no_error,
traced_out_state,
atol=1e-6)
# Test that we cannot correct a Z error. In this case, they manifest as a phase error, so we
# test the state vectors.
_, traced_out_state_no_error = encode_corrupt_correct(bit_flip_code,
input_val=1,
error_gate=None,
error_loc=None)
_, traced_out_state_z1_error = encode_corrupt_correct(bit_flip_code,
input_val=1,
error_gate=cirq.Z,
error_loc=1)
with np.testing.assert_raises(AssertionError):
np.testing.assert_allclose(traced_out_state_no_error,
traced_out_state_z1_error,
atol=1e-6)
def test_no_error():
# Table 3.2.
five_qubit_code = sc.StabilizerCode(
group_generators=['XZZXI', 'IXZZX', 'XIXZZ', 'ZXIXZ'], correctable_errors=['X', 'Z']
)
for input_val in [0, 1]:
decoded, _ = encode_corrupt_correct(
five_qubit_code, input_val, error_gate=None, error_loc=None
)
assert decoded == input_val
def test_errors(group_generators):
code = sc.StabilizerCode(group_generators=group_generators, correctable_errors=['X', 'Z'])
for input_val in [0, 1]:
_, traced_out_state_no_error = encode_corrupt_correct(
code, input_val, error_gate=None, error_loc=None
)
for error_gate in [cirq.X, cirq.Z]:
for error_loc in range(code.n):
decoded, traced_out_state = encode_corrupt_correct(
code, input_val, error_gate, error_loc
)
assert decoded == input_val
np.testing.assert_allclose(traced_out_state_no_error, traced_out_state, atol=1e-6)