def test_amplitudes_and_probs_output_type(self, wf: Wavefunction):
if len(wf.free_symbols) > 0:
assert wf.amplitudes.dtype == object
assert wf.probabilities().dtype == object
else:
assert wf.amplitudes.dtype == np.complex128
assert wf.probabilities().dtype == np.float64
def test_eq_returns_true_for_objects_with_equal_wavefunctions(
self, symbolic_wf: Wavefunction, numeric_wf: Wavefunction):
test_wf = Wavefunction(symbolic_wf._amplitude_vector)
assert symbolic_wf == test_wf
test_wf = Wavefunction(numeric_wf._amplitude_vector)
np.testing.assert_array_equal(numeric_wf, test_wf)
def test_string_output_of_numeric_wavefunction(self):
wf = Wavefunction([1j, 0])
wf_str = wf.__str__()
assert "j" in wf_str
assert wf_str.endswith("])")
assert wf_str.startswith("Wavefunction([")
def test_string_output_of_symbolic_wavefunction(self):
wf = Wavefunction([Symbol("alpha"), 0])
wf_str = wf.__str__()
assert "alpha" in wf_str
assert wf_str.endswith("])")
assert wf_str.startswith("Wavefunction([")
def test_get_outcome_probs(self, wf_vec):
wf = Wavefunction(wf_vec)
probs_dict = wf.get_outcome_probs()
assert all([len(key) == wf.n_qubits for key in probs_dict.keys()])
for key in probs_dict.keys():
assert len(key) == wf.n_qubits
assert wf.probabilities()[int(key, 2)] == probs_dict[key]
class TestRepresentations:
def test_string_output_of_symbolic_wavefunction(self):
wf = Wavefunction([Symbol("alpha"), 0])
wf_str = wf.__str__()
assert "alpha" in wf_str
assert wf_str.endswith("])")
assert wf_str.startswith("Wavefunction([")
def test_string_output_of_numeric_wavefunction(self):
wf = Wavefunction([1j, 0])
wf_str = wf.__str__()
assert "j" in wf_str
assert wf_str.endswith("])")
assert wf_str.startswith("Wavefunction([")
@pytest.mark.parametrize(
"wf",
[Wavefunction.init_system(2),
Wavefunction([Symbol("alpha"), 0.0])])
def test_amplitudes_and_probs_output_type(self, wf: Wavefunction):
if len(wf.free_symbols) > 0:
assert wf.amplitudes.dtype == object
assert wf.probabilities().dtype == object
else:
assert wf.amplitudes.dtype == np.complex128
assert wf.probabilities().dtype == np.float64
@pytest.mark.parametrize(
"wf_vec",
[
[1.0, 0.0],
[0.5, 0.5, 0.5, 0.5],
[1 / sqrt(2), 0, 0, 0, 0, 0, 0, 1 / sqrt(2)],
],
)
def test_get_outcome_probs(self, wf_vec):
wf = Wavefunction(wf_vec)
probs_dict = wf.get_outcome_probs()
assert all([len(key) == wf.n_qubits for key in probs_dict.keys()])
for key in probs_dict.keys():
assert len(key) == wf.n_qubits
assert wf.probabilities()[int(key, 2)] == probs_dict[key]
def test_binding_all_symbols_returns_numpy_array(
self, symbolic_wf: Wavefunction):
assert isinstance(
symbolic_wf.bind({
"alpha": 0.5,
"beta": 0.5
})._amplitude_vector, np.ndarray)
def sample_from_wavefunction(
wavefunction: Wavefunction,
n_samples: int,
seed: Optional[int] = None,
) -> List[Tuple[int, ...]]:
"""Sample bitstrings from a wavefunction.
Args:
wavefunction: the wavefunction to sample from.
n_samples: the number of samples taken. Needs to be greater than 0.
seed: the seed of the sampler
Returns:
List[Tuple[int]]: A list of tuples where the each tuple is a sampled bitstring.
"""
assert isinstance(n_samples, int) and n_samples > 0
rng = np.random.default_rng(seed)
outcomes_str, probabilities_np = zip(
*wavefunction.get_outcome_probs().items())
probabilities = [
x[0] if isinstance(x, (list, np.ndarray)) else x
for x in list(probabilities_np)
]
samples_ndarray = rng.choice(a=outcomes_str,
size=n_samples,
p=probabilities)
samples = [
tuple(int(y) for y in list(x)[::-1]) for x in list(samples_ndarray)
]
return samples
def test_sample_from_wavefunction_fails_for_invalid_n_samples(n_samples):
n_qubits = 4
amplitudes = [0] * (2**n_qubits)
amplitudes[1] = 1
wavefunction = Wavefunction(amplitudes)
with pytest.raises(AssertionError):
sample_from_wavefunction(wavefunction, n_samples)
def get_wavefunction(
self,
circuit: Circuit,
initial_state: Optional[StateVector] = None) -> Wavefunction:
"""Returns a wavefunction representing quantum state produced by a circuit
Args:
circuit: quantum circuit to be executed.
initial_state: a state from which the simulation starts.
If not provided, the default |0...0> is used.
"""
if initial_state is None:
state = np.zeros(2**circuit.n_qubits)
state[0] = 1
else:
state = initial_state
for is_supported, subcircuit in split_circuit(
circuit, self.is_natively_supported):
# Native subcircuits are passed through to the underlying simulator.
# They also count towards number of circuits and number of jobs run.
if is_supported:
self.number_of_circuits_run += 1
self.number_of_jobs_run += 1
state = self._get_wavefunction_from_native_circuit(
subcircuit, state)
else:
for operation in subcircuit.operations:
state = operation.apply(state)
return Wavefunction(state)
class TestGates:
@pytest.fixture
def simulator(self) -> SymbolicSimulator:
return SymbolicSimulator()
@pytest.mark.parametrize(
"circuit, expected_wavefunction",
[
(
Circuit([RX(Symbol("theta"))(0)]),
Wavefunction([
1.0 * cos(Symbol("theta") / 2),
-1j * sin(Symbol("theta") / 2)
]),
),
(
Circuit([X(0), RY(Symbol("theta"))(0)]),
Wavefunction([
-1.0 * sin(Symbol("theta") / 2),
1.0 * cos(Symbol("theta") / 2),
]),
),
(
Circuit([
H(0),
U3(Symbol("theta"), Symbol("phi"), Symbol("lambda"))(0)
]),
Wavefunction([
cos(Symbol("theta") / 2) / sqrt(2) +
-exp(I * Symbol("lambda")) * sin(Symbol("theta") / 2) /
sqrt(2),
exp(I * Symbol("phi")) * sin(Symbol("theta") / 2) / sqrt(2)
+ exp(I * (Symbol("lambda") + Symbol("phi"))) *
cos(Symbol("theta") / 2) / sqrt(2),
]),
),
],
)
def test_wavefunction_works_as_expected_with_symbolic_circuits(
self,
simulator: SymbolicSimulator,
circuit: Circuit,
expected_wavefunction: Wavefunction,
):
returned_wavefunction = simulator.get_wavefunction(circuit)
assert returned_wavefunction == expected_wavefunction
def _get_wavefunction_from_native_circuit(self, circuit: Circuit,
initial_state) -> Wavefunction:
state = initial_state
for operation in circuit.operations:
state = operation.apply(state)
return Wavefunction(state)
def test_sample_from_wavefunction_column_vector():
n_qubits = 4
expected_bitstring = (0, 0, 0, 1)
amplitudes = np.array([0] * (2**n_qubits)).reshape(2**n_qubits, 1)
amplitudes[1] = 1 # |0001> will be measured in all cases.
wavefunction = Wavefunction(amplitudes)
sample = set(sample_from_wavefunction(wavefunction, 500))
assert len(sample) == 1
assert sample.pop() == expected_bitstring
def test_sample_from_wavefunction_list():
n_qubits = 4
expected_bitstring = (0, 0, 0, 1)
amplitudes = [0] * (2**n_qubits)
amplitudes[1] = 1 # |0001> will be measured in all cases.
wavefunction = Wavefunction(amplitudes)
sample = set(sample_from_wavefunction(wavefunction, 500))
assert len(sample) == 1
assert sample.pop() == expected_bitstring
def create_random_wavefunction(n_qubits, seed=None):
if seed:
np.random.seed(seed)
random_vector = [
complex(a, b) for a, b in zip(np.random.rand(2**n_qubits),
np.random.rand(2**n_qubits))
]
normalization_factor = np.sqrt(np.sum(np.abs(random_vector)**2))
random_vector /= normalization_factor
return Wavefunction(random_vector)
def test_get_expectation_value(self):
"""Check <Z0> and <Z1> for the state |100>"""
# Given
wf = Wavefunction([0, 1, 0, 0, 0, 0, 0, 0])
op1 = QubitOperator("Z0")
op2 = QubitOperator("Z1")
# When
exp_op1 = get_expectation_value(op1, wf, True)
exp_op2 = get_expectation_value(op2, wf, True)
# Then
self.assertAlmostEqual(-1, exp_op1)
self.assertAlmostEqual(1, exp_op2)
def test_init_system_returns_expected_wavefunction_size(self, n_qubits):
wavefunction = Wavefunction.init_system(n_qubits=n_qubits)
# Check length
assert len(wavefunction) == 2**n_qubits
# Check internal property
assert wavefunction.n_qubits == n_qubits
# Check amplitude of zero state
assert wavefunction[0] == 1.0
# Check amplitude of the rest of the states
assert not np.any(wavefunction[1:])
def load_wavefunction(file: LoadSource) -> Wavefunction:
"""Load a qubit wavefunction from a file.
Args:
file (str or file-like object): the name of the file, or a file-like object.
Returns:
wavefunction (zquantum.core.Wavefunction): the wavefunction object
"""
if isinstance(file, str):
with open(file, "r") as f:
data = json.load(f)
else:
data = json.load(file)
wavefunction = Wavefunction(convert_dict_to_array(data["amplitudes"]))
return wavefunction
def jw_get_ground_state_at_particle_number(
particle_number: int, qubit_operator: Union[str, SymbolicOperator]):
"""Get the ground state wavefunction of the operator for the input particle number.
Outputs are serialized to JSON within the files: "ground-state.json" and
"value-estimate.json".
Args:
particle_number: The given number of particles in the system
qubit_operator: The operator for which to find the ground state
"""
if isinstance(qubit_operator, str):
qubit_operator = load_qubit_operator(qubit_operator)
sparse_matrix = qubit_operator_sparse(qubit_operator)
ground_energy, ground_state_amplitudes = _jw_get_ground_state_at_particle_number(
sparse_matrix, particle_number)
ground_state = Wavefunction(ground_state_amplitudes)
value_estimate = ValueEstimate(ground_energy)
save_wavefunction(ground_state, "ground-state.json")
save_value_estimate(value_estimate, "value-estimate.json")
def test_imag_wavefunction_io():
wf = Wavefunction([0, 1j, 0, 0, 0, 0, 0, 0])
save_wavefunction(wf, "wavefunction.json")
loaded_wf = load_wavefunction("wavefunction.json")
assert np.allclose(wf.amplitudes, loaded_wf.amplitudes)
remove_file_if_exists("wavefunction.json")
def test_init_system_returns_numpy_array(self):
wf = Wavefunction.init_system(2)
assert isinstance(wf._amplitude_vector, np.ndarray)
def test_constructor_returns_sympy_matrix_for_free_symbols(self):
wf = Wavefunction([0.25, 0, Symbol("alpha"), 0])
assert isinstance(wf._amplitude_vector, Matrix)
def symbolic_wf(self) -> Wavefunction:
return Wavefunction([Symbol("alpha"), 0.5, Symbol("beta"), 0.5])
def test_init_system_fails_on_invalid_params(self, n_qubits):
with pytest.raises(ValueError):
Wavefunction.init_system(n_qubits=n_qubits)
def test_init_system_raises_warning_for_non_ints(self):
with pytest.warns(UserWarning):
Wavefunction.init_system(1.234)
def test_init_fails_when_passed_list_has_free_symbols_and_exceeds_unity(
self, input_list):
with pytest.raises(ValueError):
Wavefunction(input_list)
def test_flipped_wavefunction_comprises_expected_amplitudes(
input_amplitudes, expected_output_amplitudes):
np.testing.assert_array_equal(
flip_wavefunction(Wavefunction(input_amplitudes)).amplitudes,
expected_output_amplitudes,
)
def numeric_wf(self) -> Wavefunction:
return Wavefunction([0.5, 0.5, 0.5, 0.5])
def test_init_fails_when_len_of_passed_list_is_not_power_of_two(
self, input_list):
with pytest.raises(ValueError):
Wavefunction(input_list)
def test_constructor_returns_numpy_array_for_no_symbols(self):
wf = Wavefunction([1.0, 0, 0, 0])
assert isinstance(wf._amplitude_vector, np.ndarray)