Hello!
I want to compute the Jacobian of a QNode which has a tuple of measurement results as output. I am referring to the example shown in qml.jacobian — PennyLane 0.38.0 documentation. However, I am getting an error for the example given in that page. Not sure if it has to do with the python package versions that I am using. I would truly appreciate if someone can help me run this example. I have attached my code and error message here. Thank you very much in advance!
import pennylane as qml
from pennylane import numpy as np
dev = qml.device("default.qubit", wires=2)
print(qml.about())
@qml.qnode(dev)
def circuit(x, y, z):
qml.RX(x, wires=0)
qml.RY(y, wires=1)
qml.RZ(z, wires=0)
return tuple(qml.expval(qml.Z(w)) for w in dev.wires)
x = np.array(0.2, requires_grad=True)
y = np.array(0.9, requires_grad=True)
z = np.array(-1.4, requires_grad=True)
jac = qml.jacobian(circuit)(x, y, z)
please find the full error message below:
UserWarning: Output seems independent of input.
warnings.warn("Output seems independent of input.")
Traceback (most recent call last):
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\numpy\core\fromnumeric.py", line 59, in _wrapfunc
return bound(*args, **kwds)
^^^^^^^^^^^^^^^^^^^^
TypeError: 'ArrayVSpace' object cannot be interpreted as an integer
During handling of the above exception, another exception occurred:
Traceback (most recent call last):
File "C:\Users\hedge\AppData\Roaming\JetBrains\PyCharmEdu2022.1\scratches\scratch.py", line 19, in <module>
jac = qml.jacobian(circuit)(x, y, z)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\pennylane\_grad.py", line 456, in _jacobian_function
jac = tuple(_jacobian(func, arg)(*args, **kwargs) for arg in _argnum)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\pennylane\_grad.py", line 456, in <genexpr>
jac = tuple(_jacobian(func, arg)(*args, **kwargs) for arg in _argnum)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\autograd\wrap_util.py", line 20, in nary_f
return unary_operator(unary_f, x, *nary_op_args, **nary_op_kwargs)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\autograd\differential_operators.py", line 64, in jacobian
return np.reshape(np.stack(grads), jacobian_shape)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\autograd\tracer.py", line 48, in f_wrapped
return f_raw(*args, **kwargs)
^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\numpy\core\fromnumeric.py", line 285, in reshape
return _wrapfunc(a, 'reshape', newshape, order=order)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\numpy\core\fromnumeric.py", line 68, in _wrapfunc
return _wrapit(obj, method, *args, **kwds)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
File "C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages\numpy\core\fromnumeric.py", line 45, in _wrapit
result = getattr(asarray(obj), method)(*args, **kwds)
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
TypeError: 'ArrayVSpace' object cannot be interpreted as an integer
the output of qml.about():
Name: PennyLane
Version: 0.37.0
Summary: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network.
Home-page: GitHub - PennyLaneAI/pennylane: PennyLane is a cross-platform Python library for quantum computing, quantum machine learning, and quantum chemistry. Train a quantum computer the same way as a neural network.
Author:
Author-email:
License: Apache License 2.0
Location: C:\Users\hedge\PycharmProjects\cfd-quantum\venv\Lib\site-packages
Requires: appdirs, autograd, autoray, cachetools, networkx, numpy, packaging, pennylane-lightning, requests, rustworkx, scipy, semantic-version, toml, typing-extensions
Required-by: PennyLane_Lightning
Platform info: Windows-10-10.0.22631-SP0
Python version: 3.11.9
Numpy version: 1.26.4
Scipy version: 1.14.1
Installed devices:
- default.clifford (PennyLane-0.37.0)
- default.gaussian (PennyLane-0.37.0)
- default.mixed (PennyLane-0.37.0)
- default.qubit (PennyLane-0.37.0)
- default.qubit.autograd (PennyLane-0.37.0)
- default.qubit.jax (PennyLane-0.37.0)
- default.qubit.legacy (PennyLane-0.37.0)
- default.qubit.tf (PennyLane-0.37.0)
- default.qubit.torch (PennyLane-0.37.0)
- default.qutrit (PennyLane-0.37.0)
- default.qutrit.mixed (PennyLane-0.37.0)
- default.tensor (PennyLane-0.37.0)
- null.qubit (PennyLane-0.37.0)
- lightning.qubit (PennyLane_Lightning-0.37.0)
None
