Qiskit is an open-source framework for working with Noisy Intermediate-Scale Quantum (NISQ) computers at the level of pulses, circuits, and algorithms.

Qiskit is made up of elements that work together to enable quantum computing. This element is Terra and is the foundation on which the rest of Qiskit is built.

We encourage installing Qiskit via the pip tool (a python package manager), which installs all Qiskit elements, including Terra.

pip install qiskit

PIP will handle all dependencies automatically and you will always install the latest (and well-tested) version.

To install from source, follow the instructions in the contribution guidelines.

Now that Qiskit is installed, it's time to begin working with Terra.

We are ready to try out a quantum circuit example, which is simulated locally using the Qiskit BasicAer element. This is a simple example that makes an entangled state.

$ python

>>> from qiskit import *
>>> q = QuantumRegister(2)
>>> c = ClassicalRegister(2)
>>> qc = QuantumCircuit(q, c)
>>> qc.h(q[0])
>>> qc.cx(q[0], q[1])
>>> qc.measure(q, c)
>>> backend_sim = BasicAer.get_backend('qasm_simulator')
>>> result = execute(qc, backend_sim).result()
>>> print(result.get_counts(qc))

In this case, the output will be:

{'00': 513, '11': 511}

A script is available here, where we also show how to run the same program on a real quantum computer via IBMQ.

You can also use Qiskit to execute your code on a real quantum chip. In order to do so, you need to configure Qiskit for using the credentials in your IBM Q account:

1. Create an IBM Q > Account if you haven't already done so.

2. Get an API token from the IBM Q website under My Account > Advanced > API Token.

3. Take your token from step 2, here called MY_API_TOKEN, and run:

   >>> from qiskit import IBMQ
   >>> IBMQ.save_account('MY_API_TOKEN')

4. If you have access to the IBM Q Network features, you also need to pass the URL listed on your IBM Q account page to save_account.

After calling IBMQ.save_account(), your credentials will be stored on disk. Once they are stored, at any point in the future you can load and use them in your program simply via:

>>> from qiskit import IBMQ
>>> IBMQ.load_accounts()

Those who do not want to save their credentials to disk should use instead:

>>> from qiskit import IBMQ
>>> IBMQ.enable_account('MY_API_TOKEN')

and the token will only be active for the session. For examples using Terra with real devices we have provided a set of examples in examples/python and we suggest starting with using_qiskit_terra_level_0.py and working up in the levels.

If you'd like to contribute to Qiskit Terra, please take a look at our contribution guidelines. This project adheres to Qiskit's code of conduct. By participating, you are expected to uphold this code.

We use GitHub issues for tracking requests and bugs. Please join the Qiskit Slack community and use our Qiskit Slack channel for discussion and simple questions. For questions that are more suited for a forum we use the Qiskit tag in the Stack Exchange.

Now you're set up and ready to check out some of the other examples from our Qiskit Tutorials repository.

Qiskit Terra is the work of many people who contribute to the project at different levels. If you use Qiskit, please cite as per the included BibTeX file.

Apache License 2.0