Frequently Asked Questions¶
Q: How should I cite Qiskit in my research?
A: Please cite Qiskit by using the included BibTeX file.
Q: Why do I receive the error message AttributeError: QuantumCircuit object has no attribute save_state
when using ``save_*``method on a circuit?
A: The save_* instructions are part of Qiskit Aer project,
a high performance simulator for quantum circuits. These instructions do not
exist outside of Qiskit Aer and are added dynamically to the
QuantumCircuit class by Qiskit Aer on import. If you would like to
use these instructions you must first ensure that you have imported
qiskit_aer in your program before trying to call these methods. You
can refer to qiskit_aer.library for the details of these custom
instructions included with Qiskit Aer.
Q: Why do my results from real devices differ from my results from the simulator?
A: The simulator runs jobs as though is was in an ideal environment; one without noise or decoherence. However, when jobs are run on the real devices there is noise from the environment and decoherence, which causes the qubits to behave differently than what is intended.
Q: Why do I receive the error message, No Module 'qiskit' when using Jupyter Notebook?
A: If you used pip install qiskit and set up your virtual environment in
Anaconda, then you may experience this error when you run a tutorial
in Jupyter Notebook. If you have not installed Qiskit or set up your
virtual environment, you can follow the Installation steps.
The error is caused when trying to import the Qiskit package in an environment where Qiskit is not installed. If you launched Jupyter Notebook from the Anaconda-Navigator, it is possible that Jupyter Notebook is running in the base (root) environment, instead of in your virtual environment. Choose a virtual environment in the Anaconda-Navigator from the Applications on dropdown menu. In this menu, you can see all of the virtual environments within Anaconda, and you can select the environment where you have Qiskit installed to launch Jupyter Notebook.
Q: Why am I getting a compilation error while installing ``qiskit``?
A: Qiskit depends on a number of other open source Python packages, which
are automatically installed when doing pip install qiskit. Depending on
your system’s platform and Python version, it is possible that a particular
package does not provide pre-built binaries for your system. You can refer
to Platform Support for a list of platforms supported by Qiskit, some
of which may need an extra compiler. In cases where there are
no precompiled binaries available pip will attempt to compile the package
from source, which in turn might require some extra dependencies that need to
be installed manually.
If the output of pip install qiskit contains similar lines to:
Failed building wheel for SOME_PACKAGE
...
build/temp.linux-x86_64-3.5/_openssl.c:498:30: fatal error
compilation terminated.
error: command 'x86_64-linux-gnu-gcc' failed with exit status 1
please check the documentation of the package that failed to install (in the
example code, SOME_PACKAGE) for information on how to install the libraries
needed for compiling from source.