Hello!
I’ve been trying to implement certain pennylane tutorials on qiskit backend. A week ago, i.e., when I had Pennylane v27, everything worked fine with just
dev = qml.device('qiskit.aer',wires=tot_qubits)
@qml.qnode(dev)
The tutorial I’m trying to implement is the VQLS tutorial. However, as I updated to v31 and tried to run this command again, I get a problem in the calculation of cost function (Variational Quantum Linear Solver | PennyLane Demos), the error originates at the calculation of cost and is an attribute error.
w, cost = opt.step_and_cost(cost_loc, w)
g, forward = self.compute_grad(objective_fn, args, kwargs, grad_fn=grad_fn)
AttributeError: 'list' object has no attribute 'measurements'
And, finally, here is the output of qml.about() :
Name: PennyLane
Version: 0.31.1
Summary: PennyLane is a Python quantum machine learning library by Xanadu Inc.
Home-page: https://github.com/PennyLaneAI/pennylane
Author:
Author-email:
License: Apache License 2.0
Location: /p/bv/bin/soft/Python-3.8.6/lib/python3.8/site-packages
Requires: appdirs, autograd, autoray, cachetools, networkx, numpy, pennylane-lightning, requests, rustworkx, scipy, semantic-version, toml, typing-extensions
Required-by: PennyLane-Lightning, PennyLane-qiskit
Platform info: Linux-3.10.0-1160.90.1.el7.x86_64-x86_64-with-glibc2.2.5
Python version: 3.8.6
Numpy version: 1.23.2
Scipy version: 1.9.3
Installed devices:
- default.gaussian (PennyLane-0.31.1)
- default.mixed (PennyLane-0.31.1)
- default.qubit (PennyLane-0.31.1)
- default.qubit.autograd (PennyLane-0.31.1)
- default.qubit.jax (PennyLane-0.31.1)
- default.qubit.tf (PennyLane-0.31.1)
- default.qubit.torch (PennyLane-0.31.1)
- default.qutrit (PennyLane-0.31.1)
- null.qubit (PennyLane-0.31.1)
- lightning.qubit (PennyLane-Lightning-0.31.0)
- qiskit.aer (PennyLane-qiskit-0.27.0)
- qiskit.basicaer (PennyLane-qiskit-0.27.0)
- qiskit.ibmq (PennyLane-qiskit-0.27.0)
- qiskit.ibmq.circuit_runner (PennyLane-qiskit-0.27.0)
- qiskit.ibmq.sampler (PennyLane-qiskit-0.27.0)
Is it possible that the Pennylane-qiskit needs to go from v27 to v31 so this error is circumvented?
Thanks!