abignu
October 30, 2019, 9:32am
1
Hi, I am having an error when calling the device:
DeviceError Traceback (most recent call last)
<ipython-input-41-5e0abc3e2a88> in <module>()
4 from pennylane.plugins import default_qubit
5 import matplotlib.pyplot as plt
----> 6 dev = qml.device('default.qubit', wires=1)
7
8 # Set a random seed
/usr/local/lib/python3.6/dist-packages/pennylane/__init__.py in device(name, *args, **kwargs)
128
129 raise DeviceError(
--> 130 "Device does not exist. Make sure the required plugin is installed."
131 )
132
DeviceError: Device does not exist. Make sure the required plugin is installed.
How can I solve it?
1 Like
nathan
October 30, 2019, 1:11pm
2
Hi @abignu ,
default.qubit plugin shouldn’t need any extra installation (comes pre-packaged within pennylane). My guess would be something has gone wrong with your pennylane install. Can you try the following and tell us the output?
import pennylane as qml
qml.about()
Also, can you try uninstalling and reinstalling it and let me know how that works?
Thanks,
PS you shouldn’t need to directly import the plugin (line 4 of your code). This is handled automatically by the qml.device function.
1 Like
abignu
October 30, 2019, 2:15pm
3
Hi @nathan , thanks for your reply. I was working in Google Colab. I found on another page that restarting the runtime fixes this issue. So I have already fixed it.
Thanks for your time
Agustin
1 Like
Hi both, I’m having the same error on colab and have tried restarting the runtime a couple of times without success.
The output from qml.about() I get is:
Version: 0.7.0
Summary: PennyLane is a Python quantum machine learning library by Xanadu Inc.
Home-page: https://github.com/XanaduAI/pennylane
Author: None
Author-email: None
License: Apache License 2.0
Location: /usr/local/lib/python3.6/dist-packages
Requires: toml, networkx, numpy, autograd, appdirs, semantic-version, scipy
Required-by: PennyLane-qiskit
Platform info: Linux-4.14.137+-x86_64-with-Ubuntu-18.04-bionic
Python version: 3.6.9
Numpy version: 1.17.5
Scipy version: 1.4.1
Installed devices:
This is what I’m doing to install it: https://colab.research.google.com/drive/1bPipFzEuYgNPLVeJ5HXVP-kpG1o5QFmJ which I’m basing on https://pennylane.ai/install.html
Ignore me, restarted it again and it works
1 Like
I had the same problem with google collab, then I used this code snippet to restart runtime
import os
def restart_runtime():
os.kill(os.getpid(), 9)
restart_runtime()
Calling qml.about() should have the following output
Name: PennyLane
Version: 0.8.1
Summary: PennyLane is a Python quantum machine learning library
by Xanadu Inc.
Home-page: https://github.com/XanaduAI/pennylane
Author: None
Author-email: None
License: Apache License 2.0
Location: /usr/local/lib/python3.6/dist-packages
Requires: appdirs, networkx, scipy, semantic-version, numpy, toml,
autograd
Required-by:
Platform info: Linux-4.14.137+-x86_64-with-Ubuntu-18.04-bionic
Python version: 3.6.9
Numpy version: 1.17.5
Scipy version: 1.4.1
Installed devices:
- default.gaussian (PennyLane-0.8.1)
- default.qubit (PennyLane-0.8.1)
- default.tensor (PennyLane-0.8.1)
- default.tensor.tf (PennyLane-0.8.1)
nathan
March 2, 2020, 6:54pm
8
If you’re working manually in a colab notebook, it should also be sufficient (and probably safer?) to restart the runtime via the available menu commands (i.e., no need to script it in python)
Thank you so much!
Very helpful.
Thank you for posting this query
Hi, I am having an issue in loading the device default.tensor.tf on Pennylane 0.11.0.
dev = qml.device('default.tensor.tf', wires=4)
This gives the following error:
ImportError: default.tensor device requires TensorNetwork>=0.3
This is the complete error message:
ModuleNotFoundError Traceback (most recent call last)
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-
packages\pennylane\beta\devices\default_tensor.py in <module>
26 try:
---> 27 import tensornetwork as tn
28 ModuleNotFoundError: No module named 'tensornetwork'
During handling of the above exception, another exception occurred:
ImportError Traceback (most recent call last)
<ipython-input-3-385680400a10> in <module>
----> 1 dev = qml.device('default.tensor.tf', wires=4)
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-
packages\pennylane\__init__.py in device(name, *args, **kwargs)
182
183 # loads the plugin device class
--> 184 plugin_device_class = plugin_devices[name].load()
185
186 if Version(version()) not in
Spec(plugin_device_class.pennylane_requires):
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-
packages\pkg_resources\__init__.py in load(self, require, *args,
**kwargs)
2448 if require:
2449 self.require(*args, **kwargs)
-> 2450 return self.resolve()
2451
2452 def resolve(self):
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-packages\pkg_resources\__init__.py in resolve(self)
2454 Resolve the entry point from its module and attrs.
2455 """
-> 2456 module = __import__(self.module_name, fromlist=['__name__'], level=0)
2457 try:
2458 return functools.reduce(getattr, self.attrs, module)
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-packages\pennylane\beta\devices\__init__.py in <module>
17 .. currentmodule:: pennylane.beta.devices
18 """
---> 19 from .default_tensor import DefaultTensor
20 from .default_tensor_tf import DefaultTensorTF
C:\ProgramData\Anaconda3\envs\tf-gpu\lib\site-packages\pennylane\beta\devices\default_tensor.py in <module>
31 raise ImportError("default.tensor device requires TensorNetwork>=0.3")
32 except ImportError as e:
---> 33 raise ImportError("default.tensor device requires TensorNetwork>=0.3")
34
35
ImportError: default.tensor device requires TensorNetwork>=0.3
The error persists even after upgrading my tensorflow version to 2.3.0
import tensorflow as tf
print(tf.__version__)
2.3.0
How to resolve this?
josh
September 23, 2020, 6:19pm
13
HI @Vineesha ! You will need to install TensorNetwork in order to use this device. You can do this via pip:
pip install tensornetwork==0.3
1 Like
DeviceError: Device does not exist. Make sure the required plugin is installed.
Please reply solution. Error is same
josh
October 16, 2020, 9:54am
16
Hi @Amandeep , what device are you using?
If you want to use a device from an external plugin, the plugin will need to be separately installed using pip before the device is available.
If you are using PennyLane with Google Colab, you will need to restart the runtime (Runtime → Restart Runtime) before any PennyLane devices are available.
device=qiskit.aer and i am not using google colab.
josh
October 16, 2020, 4:24pm
18
device=qiskit.aer and i am not using google colab.
To access the qiskit.aer device, you will need to install the PennyLane-Qiskit plugin , if you haven’t already:
pip install pennylane-qiskit
If you have installed the plugin already, then it could be something to do with your system configuration - could you post the output of qml.about()?
Name: PennyLanehttps://github.com/XanaduAI/pennylane
default.gaussian (PennyLane-0.11.0)
default.qubit (PennyLane-0.11.0)
default.qubit.autograd (PennyLane-0.11.0)
default.qubit.tf (PennyLane-0.11.0)
default.tensor (PennyLane-0.11.0)
default.tensor.tf (PennyLane-0.11.0)
josh
October 18, 2020, 2:19pm
20
@Amandeep it looks like the PennyLane-Qiskit plugin is not installed. You can install it using pip:
pip install pennylane-qiskit
That’s an unusual error. The 
