def test_multi_thread(self, enable_tape_mode):
"""Test that multi-threaded queuing in tape mode works correctly"""
n_qubits = 4
n_batches = 5
dev = qml.device("default.qubit", wires=n_qubits)
def circuit(inputs, weights):
for index, input in enumerate(inputs):
qml.RY(input, wires=index)
for index in range(n_qubits - 1):
qml.CNOT(wires=(index, index + 1))
for index, weight in enumerate(weights):
qml.RX(weight, wires=index)
return [qml.expval(qml.PauliZ(wires=i)) for i in range(n_qubits)]
weight_shapes = {"weights": (n_qubits)}
try:
qnode = QNodeCollection([QNode(circuit, dev) for _ in range(n_batches)])
except Exception as e:
pytest.fail("QNodeCollection cannot be instantiated")
x = np.random.rand(n_qubits).astype(np.float64)
p = np.random.rand(weight_shapes["weights"]).astype(np.float64)
try:
for _ in range(10):
qnode(x, p, parallel=True)
except:
pytest.fail("Multi-threading on QuantumTape failed")
def test_gradient_torch(self, mocker):
"""Test that caching works when calculating the gradient method using the Torch interface"""
import torch
qnode = get_qnode(caching=10, interface="torch")
args0 = torch.tensor(0.1, requires_grad=True)
args1 = torch.tensor(0.2)
res = qnode(args0, args1)
res.backward()
assert args0.grad is not None
spy = mocker.spy(DefaultQubitAutograd, "execute")
res = qnode(args0, args1)
res.backward()
spy.assert_not_called()
def test_caching(self, mocker):
"""Test that multiple device executions with different params are cached and accessed on
subsequent executions"""
qnode = get_qnode(caching=10)
args = np.arange(10)
for arg in args:
qnode(arg, 0.2)
assert qnode.qtape.caching == 10
spy = mocker.spy(DefaultQubitAutograd, "execute")
for arg in args:
qnode(arg, 0.2)
spy.assert_not_called()
def test_gradient_tf(self, mocker):
"""Test that caching works when calculating the gradient method using the TF interface"""
import tensorflow as tf
qnode = get_qnode(caching=10, interface="tf")
args0 = tf.Variable(0.1)
args1 = tf.Variable(0.2)
with tf.GradientTape() as tape:
res = qnode(args0, args1)
grad = tape.gradient(res, args0)
assert grad is not None
spy = mocker.spy(DefaultQubitAutograd, "execute")
with tf.GradientTape() as tape:
res = qnode(args0, args1)
tape.gradient(res, args0)
spy.assert_not_called()