def test_tape_mode_detection():
"""Test that the function `tape_mode_active` returns True
only if tape mode is activated."""
qml.disable_tape()
assert not qml.tape_mode_active()
qml.enable_tape()
assert qml.tape_mode_active()
def test_metric_tensor_tape_mode(self):
"""Test that the metric tensor can be calculated in tape mode, and that it is equal to a
metric tensor calculated in non-tape mode."""
if not qml.tape_mode_active():
pytest.skip("This test is only intended for tape mode")
dev = qml.device("default.qubit", wires=2)
p = np.array([1., 1., 1.])
def ansatz(params, **kwargs):
qml.RX(params[0], wires=0)
qml.RY(params[1], wires=0)
qml.CNOT(wires=[0, 1])
qml.PhaseShift(params[2], wires=1)
h = qml.Hamiltonian([1, 1], [qml.PauliZ(0), qml.PauliZ(1)])
qnodes = qml.ExpvalCost(ansatz, h, dev)
mt = qml.metric_tensor(qnodes)(p)
assert qml.tape_mode_active() # Check that tape mode is still active
qml.disable_tape()
@qml.qnode(dev)
def circuit(params):
qml.RX(params[0], wires=0)
qml.RY(params[1], wires=0)
qml.CNOT(wires=[0, 1])
qml.PhaseShift(params[2], wires=1)
return qml.expval(qml.PauliZ(0))
mt2 = circuit.metric_tensor([p])
assert np.allclose(mt, mt2)
def test_backprop_gradients(self, mocker):
"""Test if KerasLayer is compatible with the backprop diff method."""
if not qml.tape_mode_active():
pytest.skip("This functionality is only supported in tape mode.")
dev = qml.device("default.qubit.tf", wires=2)
@qml.qnode(dev, interface="tf", diff_method="backprop")
def f(inputs, weights):
qml.templates.AngleEmbedding(inputs, wires=range(2))
qml.templates.StronglyEntanglingLayers(weights, wires=range(2))
return [qml.expval(qml.PauliZ(i)) for i in range(2)]
weight_shapes = {"weights": (3, 2, 3)}
qlayer = qml.qnn.KerasLayer(f, weight_shapes, output_dim=2)
inputs = tf.ones((4, 2))
with tf.GradientTape() as tape:
out = tf.reduce_sum(qlayer(inputs))
spy = mocker.spy(qml.tape.tapes.QubitParamShiftTape, "jacobian")
grad = tape.gradient(out, qlayer.trainable_weights)
assert grad is not None
spy.assert_not_called()
def test_grad_tf(self, qnodes, skip_if_no_tf_support, parallel, interface):
"""Test correct gradient of the QNodeCollection using
the tf interface"""
if parallel and qml.tape_mode_active():
pytest.skip(
"There appears to be a race condition when constructing TF tapes in parallel"
)
qnode1, qnode2 = qnodes
# calculate the gradient of the collection using tf
params = Variable([0.5643, -0.45])
qc = qml.QNodeCollection([qnode1, qnode2])
with tf.GradientTape() as tape:
tape.watch(params)
if parallel:
with pytest.warns(UserWarning):
cost = sum(qc(params, parallel=parallel))
else:
cost = sum(qc(params, parallel=parallel))
# the gradient will be None
res = tape.gradient(cost, params).numpy()
# calculate the gradient of the QNodes individually using tf
params = Variable([0.5643, -0.45])
with tf.GradientTape() as tape:
tape.watch(params)
cost = sum(qnode1(params) + qnode2(params))
expected = tape.gradient(cost, params).numpy()
assert np.all(res == expected)
def _evaluate_qnode(self, x):
"""Evaluates the QNode for a single input datapoint.
Args:
x (tensor): the datapoint
Returns:
tensor: output datapoint
"""
if qml.tape_mode_active():
return self._evaluate_qnode_tape_mode(x)
qnode = self.qnode
for arg in self.sig:
if arg is not self.input_arg: # Non-input arguments must always be positional
w = self.qnode_weights[arg]
qnode = functools.partial(qnode, w)
else:
if self.input_is_default: # The input argument can be positional or keyword
qnode = functools.partial(qnode, **{self.input_arg: x})
else:
qnode = functools.partial(qnode, x)
return qnode().type(x.dtype)
def _preprocess(weights, initial_layer_weights, wires):
"""Validate and pre-process inputs as follows:
* Check the shapes of the two weights tensors.
Args:
weights (tensor_like): trainable parameters of the template
initial_layer_weights (tensor_like): weight tensor for the initial rotation block, shape ``(M,)``
wires (Wires): wires that template acts on
Returns:
int: number of times that the ansatz is repeated
"""
if qml.tape_mode_active():
shape = qml.math.shape(weights)
repeat = shape[0]
if len(shape) > 1:
if shape[1] != len(wires) - 1:
raise ValueError(
f"Weights tensor must have second dimension of length {len(wires) - 1}; got {shape[1]}"
)
if shape[2] != 2:
raise ValueError(
f"Weights tensor must have third dimension of length 2; got {shape[2]}"
)
shape2 = qml.math.shape(initial_layer_weights)
if shape2 != (len(wires), ):
raise ValueError(
f"Initial layer weights must be of shape {(len(wires),)}; got {shape2}"
)
else:
repeat = check_number_of_layers([weights])
expected_shape_initial = (len(wires), )
check_shape(
initial_layer_weights,
expected_shape_initial,
msg="Initial layer weights must be of shape {}; got {}"
"".format(expected_shape_initial,
get_shape(initial_layer_weights)),
)
if len(wires) in [0, 1]:
expected_shape_weights = (0, )
else:
expected_shape_weights = (repeat, len(wires) - 1, 2)
check_shape(
weights,
expected_shape_weights,
msg="Weights tensor must be of shape {}; got {}"
"".format(expected_shape_weights, get_shape(weights)),
)
return repeat
def test_exception_wrong_dim(self):
"""Verifies that exception is raised if the
number of dimensions of features is incorrect."""
if not qml.tape_mode_active():
pytest.skip("This validation is only performed in tape mode")
dev = qml.device("default.qubit", wires=4)
initial_layer = np.random.randn(2)
@qml.qnode(dev)
def circuit(initial_layer, weights):
SimplifiedTwoDesign(initial_layer, weights, wires=range(2))
return qml.expval(qml.PauliZ(0))
with pytest.raises(ValueError,
match="Weights tensor must have second dimension"):
weights = np.random.randn(2, 2, 2)
circuit(initial_layer, weights)
with pytest.raises(ValueError,
match="Weights tensor must have third dimension"):
weights = np.random.randn(2, 1, 3)
circuit(initial_layer, weights)
with pytest.raises(ValueError,
match="Initial layer weights must be of shape"):
initial_layer = np.random.randn(3)
weights = np.random.randn(2, 1, 2)
circuit(initial_layer, weights)
def test_optimize_grad(self):
"""Test that the gradient of ExpvalCost is accessible and correct when using observable
optimization and the autograd interface."""
if not qml.tape_mode_active():
pytest.skip("This test is only intended for tape mode")
dev = qml.device("default.qubit", wires=4)
hamiltonian = big_hamiltonian
cost = qml.ExpvalCost(qml.templates.StronglyEntanglingLayers,
hamiltonian,
dev,
optimize=True)
cost2 = qml.ExpvalCost(qml.templates.StronglyEntanglingLayers,
hamiltonian,
dev,
optimize=False)
w = qml.init.strong_ent_layers_uniform(2, 4, seed=1967)
dc = qml.grad(cost)(w)
exec_opt = dev.num_executions
dev._num_executions = 0
dc2 = qml.grad(cost2)(w)
exec_no_opt = dev.num_executions
assert exec_no_opt > exec_opt
assert np.allclose(dc, big_hamiltonian_grad)
assert np.allclose(dc2, big_hamiltonian_grad)
def test_qnode_collection_integration(self):
"""Test that a PassthruQNode using default.qubit.jax works with QNodeCollections."""
dev = qml.device("default.qubit.jax", wires=2)
def ansatz(weights, **kwargs):
qml.RX(weights[0], wires=0)
qml.RY(weights[1], wires=1)
qml.CNOT(wires=[0, 1])
obs_list = [
qml.PauliX(0) @ qml.PauliY(1),
qml.PauliZ(0),
qml.PauliZ(0) @ qml.PauliZ(1)
]
qnodes = qml.map(ansatz, obs_list, dev, interface="jax")
if not qml.tape_mode_active():
assert qnodes.interface == "jax"
weights = jnp.array([0.1, 0.2])
def cost(weights):
return jnp.sum(jnp.array(qnodes(weights)))
grad = jax.grad(cost)(weights)
assert grad.shape == weights.shape
def _preprocess(weight, wires):
"""Validate and pre-process inputs as follows:
* Check the shape of the weights tensor.
* Check that there are at least 2 wires.
Args:
weight (tensor_like): trainable parameters of the template
wires (Wires): wires that template acts on
"""
if len(wires) < 2:
raise ValueError("expected at least two wires; got {}".format(
len(wires)))
if qml.tape_mode_active():
shape = qml.math.shape(weight)
if shape != ():
raise ValueError(
f"Weight must be a scalar tensor {()}; got shape {shape}.")
else:
expected_shape = ()
check_shape(
weight,
expected_shape,
msg="Weight must be a scalar; got shape {}".format(
expected_shape, get_shape(weight)),
)
def _preprocess(weights):
"""Validate and pre-process inputs as follows:
* Check that the weights tensor is 2-dimensional.
Args:
weights (tensor_like): trainable parameters of the template
Returns:
int: number of times that the ansatz is repeated
"""
if qml.tape_mode_active():
shape = qml.math.shape(weights)
if len(shape) != 2:
raise ValueError(
f"Weights tensor must be 2-dimensional; got shape {shape}")
repeat = shape[0]
else:
repeat = check_number_of_layers([weights])
n_rots = get_shape(weights)[1]
expected_shape = (repeat, n_rots)
check_shape(
weights,
expected_shape,
msg="'weights' must be of shape {}; got {}"
"".format(expected_shape, get_shape(weights)),
)
return repeat
def test_optimize_grad_torch(self, torch_support):
"""Test that the gradient of ExpvalCost is accessible and correct when using observable
optimization and the Torch interface."""
if not qml.tape_mode_active():
pytest.skip("This test is only intended for tape mode")
if not torch_support:
pytest.skip("This test requires Torch")
dev = qml.device("default.qubit", wires=4)
hamiltonian = big_hamiltonian
cost = qml.ExpvalCost(
qml.templates.StronglyEntanglingLayers,
hamiltonian,
dev,
optimize=True,
interface="torch",
)
w = torch.tensor(qml.init.strong_ent_layers_uniform(2, 4, seed=1967),
requires_grad=True)
res = cost(w)
res.backward()
dc = w.grad.detach().numpy()
assert np.allclose(dc, big_hamiltonian_grad)
def test_exception_wrong_dim(self):
"""Verifies that exception is raised if the
number of dimensions of features is incorrect."""
if not qml.tape_mode_active():
pytest.skip("This validation is only performed in tape mode")
dev = qml.device("default.qubit", wires=2)
@qml.qnode(dev)
def circuit(state_vector):
MottonenStatePreparation(state_vector, wires=range(2))
return qml.expval(qml.PauliZ(0))
with pytest.raises(ValueError,
match="State vector must be a one-dimensional"):
state_vector = np.array([[0, 1]])
circuit(state_vector)
with pytest.raises(ValueError, match="State vector must be of length"):
state_vector = np.array([0, 1])
circuit(state_vector)
with pytest.raises(ValueError,
match="State vector has to be of length"):
state_vector = np.array([0, 2, 0, 0])
circuit(state_vector)
def test_optimize_grad_tf(self, tf_support):
"""Test that the gradient of ExpvalCost is accessible and correct when using observable
optimization and the TensorFlow interface."""
if not qml.tape_mode_active():
pytest.skip("This test is only intended for tape mode")
if not tf_support:
pytest.skip("This test requires TensorFlow")
dev = qml.device("default.qubit", wires=4)
hamiltonian = big_hamiltonian
cost = qml.ExpvalCost(qml.templates.StronglyEntanglingLayers,
hamiltonian,
dev,
optimize=True,
interface="tf")
w = tf.Variable(qml.init.strong_ent_layers_uniform(2, 4, seed=1967))
with tf.GradientTape() as tape:
res = cost(w)
dc = tape.gradient(res, w).numpy()
assert np.allclose(dc, big_hamiltonian_grad)
def test_exception_wrong_dim(self):
"""Verifies that exception is raised if the
number of dimensions of features is incorrect."""
if not qml.tape_mode_active():
pytest.skip("This validation is only performed in tape mode")
dev = qml.device("default.qubit", wires=2)
@qml.qnode(dev)
def circuit(weights):
StronglyEntanglingLayers(weights, wires=range(2))
return qml.expval(qml.PauliZ(0))
with pytest.raises(ValueError,
match="Weights tensor must have second dimension"):
weights = np.random.randn(2, 1, 3)
circuit(weights)
with pytest.raises(ValueError,
match="Weights tensor must have third dimension"):
weights = np.random.randn(2, 2, 1)
circuit(weights)
with pytest.raises(ValueError,
match="Weights tensor must be 3-dimensional"):
weights = np.random.randn(2, 2, 3, 1)
circuit(weights)
def metric_tensor(self,
args,
kwargs=None,
diag_approx=False,
only_construct=False):
"""Evaluate the value of the metric tensor.
Args:
args (tuple[Any]): positional (differentiable) arguments
kwargs (dict[str, Any]): auxiliary arguments
diag_approx (bool): iff True, use the diagonal approximation
only_construct (bool): Iff True, construct the circuits used for computing
the metric tensor but do not execute them, and return None.
Returns:
array[float]: metric tensor
"""
if self._multiple_devices:
warnings.warn(
"ExpvalCost was instantiated with multiple devices. Only the first device "
"will be used to evaluate the metric tensor.")
if qml.tape_mode_active():
return self._qnode_for_metric_tensor_in_tape_mode.metric_tensor(
args=args,
kwargs=kwargs,
diag_approx=diag_approx,
only_construct=only_construct)
# all the qnodes share the same ansatz so we select the first
return self.qnodes.qnodes[0].metric_tensor(
args=args,
kwargs=kwargs,
diag_approx=diag_approx,
only_construct=only_construct)
def test_direct_qnode_integration(self):
"""Test that a regular QNode renders correctly."""
dev = qml.device("default.qubit", wires=2)
@qml.qnode(dev)
def qfunc(a, w):
qml.Hadamard(0)
qml.CRX(a, wires=[0, 1])
qml.Rot(w[0], w[1], w[2], wires=[1])
qml.CRX(-a, wires=[0, 1])
return qml.expval(qml.PauliZ(0) @ qml.PauliZ(1))
res = qfunc(2.3, [1.2, 3.2, 0.7])
assert qfunc.draw() == (
" 0: ──H──╭C────────────────────────────╭C─────────╭┤ ⟨Z ⊗ Z⟩ \n"
+ " 1: ─────╰RX(2.3)──Rot(1.2, 3.2, 0.7)──╰RX(-2.3)──╰┤ ⟨Z ⊗ Z⟩ \n"
)
assert qfunc.draw(charset="ascii") == (
" 0: --H--+C----------------------------+C---------+| <Z @ Z> \n"
+ " 1: -----+RX(2.3)--Rot(1.2, 3.2, 0.7)--+RX(-2.3)--+| <Z @ Z> \n"
)
if not qml.tape_mode_active():
assert qfunc.draw(show_variable_names=True) == (
" 0: ──H──╭C─────────────────────────────╭C─────────╭┤ ⟨Z ⊗ Z⟩ \n"
+ " 1: ─────╰RX(a)──Rot(w[0], w[1], w[2])──╰RX(-1*a)──╰┤ ⟨Z ⊗ Z⟩ \n"
)
def call(self, inputs):
"""Evaluates the QNode on input data using the initialized weights.
Args:
inputs (tensor): data to be processed
Returns:
tensor: output data
"""
outputs = []
for x in inputs: # iterate over batch
if qml.tape_mode_active():
res = self._evaluate_qnode_tape_mode(x)
outputs.append(res)
else:
# The QNode can require some passed arguments to be positional and others to be
# keyword. The following loops through input arguments in order and uses
# functools.partial to bind the argument to the QNode.
qnode = self.qnode
for arg in self.sig:
if arg is not self.input_arg: # Non-input arguments must always be positional
w = self.qnode_weights[arg]
qnode = functools.partial(qnode, w)
outputs.append(self.quanv(x))
return tf.stack(outputs)
def _preprocess(weights, wires):
"""Validate and pre-process inputs as follows:
* Check the shape of the weights tensor.
Args:
weights (tensor_like): trainable parameters of the template
wires (Wires): wires that template acts on
"""
if qml.tape_mode_active():
shape = qml.math.shape(weights)
if shape != (4**len(wires) - 1, ):
raise ValueError(
f"Weights tensor must be of shape {(4 ** len(wires) - 1,)}; got {shape}."
)
else:
expected_shape = (4**len(wires) - 1, )
check_shape(
weights,
expected_shape,
msg="Weights tensor must be of shape {}; got {}."
"".format(expected_shape, get_shape(weights)),
)
def _preprocess(features, wires):
"""Validate and pre-process inputs as follows:
* Check that the features tensor is one-dimensional.
* Check that the first dimension of the features tensor
has length :math:`n`, where :math:`n` is the number of qubits.
* Check that the entries of the features tensor are zeros and ones.
Args:
features (tensor_like): input features to pre-process
wires (Wires): wires that template acts on
Returns:
array: numpy array representation of the features tensor
"""
if qml.tape_mode_active():
shape = qml.math.shape(features)
if len(shape) != 1:
raise ValueError(
f"Features must be one-dimensional; got shape {shape}.")
n_features = shape[0]
if n_features != len(wires):
raise ValueError(
f"Features must be of length {len(wires)}; got length {n_features}."
)
features = list(qml.math.toarray(features))
if set(features) != {0, 1}:
raise ValueError(
f"Basis state must only consist of 0s and 1s; got {features}")
return features
# non-tape mode
check_type(
features,
[Iterable],
msg="Features must be iterable; got type {}".format(type(features)),
)
expected_shape = (len(wires), )
check_shape(
features,
expected_shape,
msg="Features must be of shape {}; got {}"
"".format(expected_shape, get_shape(features)),
)
if any([b not in [0, 1] for b in features]):
raise ValueError(
"Basis state must only consist of 0s and 1s; got {}".format(
features))
return features
def _preprocess(parameters, pattern, wires):
"""Validate and pre-process inputs as follows:
* Check that pattern is recognised, or use default pattern if None.
* Check the dimension of the parameters
* Create wire sequence of the pattern.
Args:
parameters (tensor_like): trainable parameters of the template
pattern (str): specifies the wire pattern
wires (Wires): wires that template acts on
Returns:
wire_sequence, parameters: preprocessed pattern and parameters
"""
if isinstance(pattern, str):
_wires = wires
if pattern not in OPTIONS:
raise ValueError(f"did not recognize pattern {pattern}".format())
else:
# turn custom pattern into list of Wires objects
_wires = [Wires(w) for w in pattern]
# set "pattern" to "custom", indicating that custom settings have to be used
pattern = "custom"
# check that there are enough parameters for pattern
if parameters is not None:
if qml.tape_mode_active():
shape = qml.math.shape(parameters)
# expand dimension so that parameter sets for each unitary can be unpacked
if len(shape) == 1:
parameters = qml.math.expand_dims(parameters, 1)
else:
shape = get_shape(parameters)
# expand dimension so that parameter sets for each unitary can be unpacked
if len(shape) == 1:
parameters = [[p] for p in parameters]
# specific error message for ring edge case of 2 wires
if (pattern == "ring") and (len(wires) == 2) and (shape[0] != 1):
raise ValueError(
"the ring pattern with 2 wires is an exception and only applies one unitary"
)
num_params = PATTERN_TO_NUM_PARAMS[pattern](_wires)
if shape[0] != num_params:
raise ValueError(
"Parameters must contain entries for {} unitaries; got {} entries".format(
num_params, shape[0]
)
)
wire_sequence = PATTERN_TO_WIRES[pattern](_wires)
return wire_sequence, parameters
def _preprocess(weights, wires, init_state):
"""Validate and pre-process inputs as follows:
* Check that the weights tensor has the correct shape.
* Extract a wire list for the subroutines of this template.
* Cast initial state to a numpy array.
Args:
weights (tensor_like): trainable parameters of the template
wires (Wires): wires that template acts on
init_state (tensor_like): shape ``(len(wires),)`` tensor
Returns:
int, list[Wires], array: number of times that the ansatz is repeated, wires pattern,
and preprocessed initial state
"""
if len(wires) < 2:
raise ValueError(
"This template requires the number of qubits to be greater than one;"
"got a wire sequence with {} elements".format(len(wires)))
if qml.tape_mode_active():
shape = qml.math.shape(weights)
if len(shape) != 3:
raise ValueError(
f"Weights tensor must be 3-dimensional; got shape {shape}")
if shape[1] != len(wires) - 1:
raise ValueError(
f"Weights tensor must have second dimension of length {len(wires) - 1}; got {shape[1]}"
)
if shape[2] != 2:
raise ValueError(
f"Weights tensor must have third dimension of length 2; got {shape[2]}"
)
repeat = shape[0]
else:
repeat = get_shape(weights)[0]
expected_shape = (repeat, len(wires) - 1, 2)
check_shape(
weights,
expected_shape,
msg="Weights tensor must be of shape {}; got {}".format(
expected_shape, get_shape(weights)),
)
nm_wires = [wires.subset([l, l + 1]) for l in range(0, len(wires) - 1, 2)]
nm_wires += [wires.subset([l, l + 1]) for l in range(1, len(wires) - 1, 2)]
# we can extract the numpy representation here
# since init_state can never be differentiable
init_state = qml.math.toarray(init_state)
return repeat, nm_wires, init_state
def test_qubit_circuit_with_variable_names(
self, parameterized_qubit_qnode, drawn_parameterized_qubit_circuit_with_variable_names
):
"""Test that a parametrized qubit circuit renders correctly with variable names."""
if qml.tape_mode_active():
pytest.skip("show_variable_names not supported in tape mode")
output = parameterized_qubit_qnode.draw(show_variable_names=True)
assert output == drawn_parameterized_qubit_circuit_with_variable_names
def __init__(
self,
ansatz,
hamiltonian,
device,
interface="autograd",
diff_method="best",
optimize=False,
**kwargs,
):
coeffs, observables = hamiltonian.terms
self.hamiltonian = hamiltonian
"""Hamiltonian: the hamiltonian defining the VQE problem."""
self.qnodes = None
"""QNodeCollection: The QNodes to be evaluated. Each QNode corresponds to the expectation
value of each observable term after applying the circuit ansatz."""
self._optimize = optimize
if self._optimize:
if not qml.tape_mode_active():
raise ValueError(
"Observable optimization is only supported in tape mode. Tape "
"mode can be enabled with the command:\n"
"qml.enable_tape()"
)
obs_groupings, coeffs_groupings = qml.grouping.group_observables(observables, coeffs)
wires = device.wires.tolist()
@qml.qnode(device, interface=interface, diff_method=diff_method, **kwargs)
def circuit(*qnode_args, obs, **qnode_kwargs):
"""Converting ansatz into a full circuit including measurements"""
ansatz(*qnode_args, wires=wires, **qnode_kwargs)
return [qml.expval(o) for o in obs]
def cost_fn(*qnode_args, **qnode_kwargs):
"""Combine results from grouped QNode executions with grouped coefficients"""
total = 0
for o, c in zip(obs_groupings, coeffs_groupings):
res = circuit(*qnode_args, obs=o, **qnode_kwargs)
total += sum([r * c_ for r, c_ in zip(res, c)])
return total
self.cost_fn = cost_fn
else:
self.qnodes = qml.map(
ansatz, observables, device, interface=interface, diff_method=diff_method, **kwargs
)
self.cost_fn = qml.dot(coeffs, self.qnodes)
def _preprocess(weights, wires, ranges):
"""Validate and pre-process inputs as follows:
* Check the shape of the weights tensor.
* If ranges is None, define a default.
Args:
weights (tensor_like): trainable parameters of the template
wires (Wires): wires that template acts on
ranges (Sequence[int]): range for each subsequent layer
Returns:
int, list[int]: number of times that the ansatz is repeated and preprocessed ranges
"""
if qml.tape_mode_active():
shape = qml.math.shape(weights)
repeat = shape[0]
if len(shape) != 3:
raise ValueError(
f"Weights tensor must be 3-dimensional; got shape {shape}")
if shape[1] != len(wires):
raise ValueError(
f"Weights tensor must have second dimension of length {len(wires)}; got {shape[1]}"
)
if shape[2] != 3:
raise ValueError(
f"Weights tensor must have third dimension of length 3; got {shape[2]}"
)
else:
repeat = check_number_of_layers([weights])
expected_shape = (repeat, len(wires), 3)
check_shape(
weights,
expected_shape,
msg="Weights tensor must be of shape {}; got {}"
"".format(expected_shape, get_shape(weights)),
)
if len(wires) > 1:
if ranges is None:
# tile ranges with iterations of range(1, n_wires)
ranges = [(l % (len(wires) - 1)) + 1 for l in range(repeat)]
else:
ranges = [0] * repeat
return repeat, ranges
def wrapper(*args, **kwargs):
import pennylane as qml
recorder_class = OperationRecorder
if qml.tape_mode_active():
recorder_class = qml.tape.TapeOperationRecorder
with recorder_class() as rec:
func(*args, **kwargs)
return rec.queue
def test_train_model_dm(self, model_dm, batch_size, n_qubits, output_dim):
"""Test if a model can train using the KerasLayer when QNode returns a density_matrix().
The model is composed of two KerasLayers sandwiched between Dense neural network layers,
and the dataset is simply input and output vectors of zeros."""
if not qml.tape_mode_active():
pytest.skip()
x = np.zeros((batch_size, n_qubits))
y = np.zeros((batch_size, output_dim[0] * output_dim[1]))
model_dm.compile(optimizer="sgd", loss="mse")
model_dm.fit(x, y, batch_size=batch_size, verbose=0)
def _preprocess(basis_state, wires):
"""Validate and pre-process inputs as follows:
* Check the shape of the basis state.
* Cast basis state to a numpy array.
Args:
basis_state (tensor_like): basis state to prepare
wires (Wires): wires that template acts on
Returns:
array: preprocessed basis state
"""
if qml.tape_mode_active():
shape = qml.math.shape(basis_state)
if len(shape) != 1:
raise ValueError(f"Basis state must be one-dimensional; got shape {shape}.")
n_bits = shape[0]
if n_bits != len(wires):
raise ValueError(f"Basis state must be of length {len(wires)}; got length {n_bits}.")
basis_state = list(qml.math.toarray(basis_state))
if not all(bit in [0, 1] for bit in basis_state):
raise ValueError(f"Basis state must only consist of 0s and 1s; got {basis_state}")
# we return the input as a list of values, since
# it is not differentiable
return basis_state
expected_shape = (len(wires),)
check_shape(
basis_state,
expected_shape,
msg="Basis state must be of shape {}; got {}."
"".format(expected_shape, get_shape(basis_state)),
)
# basis_state is guaranteed to be a list of binary values
if any([b not in [0, 1] for b in basis_state]):
raise ValueError(
"Basis state must only contain values of 0 and 1; got {}".format(basis_state)
)
return basis_state
def test_non_input_defaults_tape_mode(self):
"""Test that everything works when default arguments that are not the input argument are
present in the QNode in tape mode"""
if not qml.tape_mode_active():
pytest.skip("This functionality is only supported in tape mode.")
n_qubits = 2
output_dim = 2
dev = qml.device("default.qubit", wires=n_qubits)
w = {
"w1": (3, n_qubits, 3),
"w2": (1, ),
"w3": 1,
"w4": [3],
"w5": (2, n_qubits, 3),
"w6": 3,
"w7": 0,
}
@qml.qnode(dev, interface="tf")
def c(inputs, w1, w2, w4, w5, w6, w7, w3=0.5):
"""A circuit that embeds data using the AngleEmbedding and then performs a variety of
operations. The output is a PauliZ measurement on the first output_dim qubits. One set of
parameters, w5, are specified as non-trainable."""
qml.templates.AngleEmbedding(inputs, wires=list(range(n_qubits)))
qml.templates.StronglyEntanglingLayers(w1,
wires=list(range(n_qubits)))
qml.RX(w2[0], wires=0 % n_qubits)
qml.RX(w3, wires=1 % n_qubits)
qml.Rot(*w4, wires=2 % n_qubits)
qml.templates.StronglyEntanglingLayers(w5,
wires=list(range(n_qubits)))
qml.Rot(*w6, wires=3 % n_qubits)
qml.RX(w7, wires=4 % n_qubits)
return [qml.expval(qml.PauliZ(i)) for i in range(output_dim)]
layer = KerasLayer(c, w, output_dim=output_dim)
x = tf.ones((2, n_qubits))
layer_out = layer(x)
circ_weights = layer.qnode_weights.copy()
circ_weights["w4"] = tf.convert_to_tensor(
circ_weights["w4"]) # To allow for slicing
circ_weights["w6"] = tf.convert_to_tensor(circ_weights["w6"])
circuit_out = c(x[0], **circ_weights)
assert np.allclose(layer_out, circuit_out)
def test_jax_interface_gradient(self, operation, diff_method, tol):
"""Tests that the gradient of an arbitrary U3 gate is correct
using the Jax interface, using a variety of differentiation methods."""
dev = qml.device("default.qubit.jax", wires=1)
@qml.qnode(dev, diff_method=diff_method, interface="jax")
def circuit(x, weights, w=None):
"""In this example, a mixture of scalar
arguments, array arguments, and keyword arguments are used."""
qml.QubitStateVector(1j * jnp.array([1, -1]) / jnp.sqrt(2),
wires=w)
operation(x, weights[0], weights[1], wires=w)
return qml.expval(qml.PauliX(w))
# Check that the correct QNode type is being used.
if not qml.tape_mode_active():
if diff_method == "backprop":
assert isinstance(circuit, qml.qnodes.PassthruQNode)
assert not hasattr(circuit, "jacobian")
else:
assert not isinstance(circuit, qml.qnodes.PassthruQNode)
assert hasattr(circuit, "jacobian")
def cost(params):
"""Perform some classical processing"""
return (circuit(params[0], params[1:], w=0)**2).reshape(())
theta = 0.543
phi = -0.234
lam = 0.654
params = jnp.array([theta, phi, lam])
res = cost(params)
expected_cost = (jnp.sin(lam) * jnp.sin(phi) -
jnp.cos(theta) * jnp.cos(lam) * jnp.cos(phi))**2
assert jnp.allclose(res, expected_cost, atol=tol, rtol=0)
res = jax.grad(cost)(params)
expected_grad = (jnp.array([
jnp.sin(theta) * jnp.cos(lam) * jnp.cos(phi),
jnp.cos(theta) * jnp.cos(lam) * jnp.sin(phi) +
jnp.sin(lam) * jnp.cos(phi),
jnp.cos(theta) * jnp.sin(lam) * jnp.cos(phi) +
jnp.cos(lam) * jnp.sin(phi),
]) * 2 * (jnp.sin(lam) * jnp.sin(phi) -
jnp.cos(theta) * jnp.cos(lam) * jnp.cos(phi)))
assert jnp.allclose(res, expected_grad, atol=tol, rtol=0)