pytket is a python module for interfacing with CQC tket, a set of quantum programming tools. We currently support circuits and device architectures from numerous providers, allowing the tket tools to be used in conjunction with projects on their platforms.

pytket is available for Python 3.7, 3.8 and 3.9, on Linux, MacOS and Windows. To install, run

pip install pytket

To use pytket, you can simply import the appropriate modules into your python code or in an interactive Python notebook. We can build circuits directly using the pytket interface by creating a blank circuit and adding gates in the order we want to apply them.

from pytket import Circuit
c = Circuit(2,2) # define a circuit with 2 qubits and 2 bits
c.H(0)           # add a Hadamard gate to qubit 0
c.Rz(0.25, 0)    # add an Rz gate of angle 0.25*pi to qubit 0
c.CX(1,0)        # add a CX gate with control qubit 1 and target qubit 0
c.measure_all()  # measure qubits 0 and 1, recording the results in bits 0 and 1

Some of the extension modules define Backend s, allowing the circuits to be run on simulators or real quantum hardware. For example, pytket-qiskit grants access to the AerBackend simulator which can sample from measurements.

from pytket.extensions.qiskit import AerBackend
b = AerBackend()                # connect to the backend
b.compile_circuit(c)            # compile the circuit to satisfy the backend's requirements
handle = b.process_circuit(c, 100)  # submit the job to run the circuit 100 times
counts = b.get_result(handle).get_counts()   # retrieve and summarise the results

This prints out a summary of readouts (the final values of the classical bits) and their frequencies.

{(0, 0): 49, (1, 0): 51}

See the Getting Started page for a basic tutorial on using pytket. To get more in depth on features, see the examples. See the Pytket User Manual for an extensive introduction to pytket functionaliy and how to use it.


To use pytket in conjunction with other platforms you must download an additional separate module for each. Each one of these adds either some new methods to the pytket package to convert between the circuit representations, or some new backends to submit circuits to within pytket.

Extension modules can be installed using pip. The extensions supported by CQC are described here.


The syntax for importing backends from extension modules has changed slightly in version 0.8 of pytket. When importing FooBackend, instead of doing

from pytket.backends.something import FooBackend

you should now do

from import FooBackend

where FooBackend is defined in the pytket-bar extension module.

This may entail some changes to existing code. For example, you should change

from import AerBackend


from pytket.extensions.qiskit import AerBackend

because AerBackend is defined in the pytket-qiskit module.

(In many cases, something and bar are identical, and you just need to change backends to extensions. For example, pytket.backends.aqt becomes pytket.extensions.aqt.)

How to cite

If you wish to cite tket in any academic publications, we generally recommend citing our software overview paper for most cases.

If your work is on the topic of specific compilation tasks, it may be more appropriate to cite one of our other papers:

We are also keen for others to benchmark their compilation techniques against us. We recommend checking our benchmark repository for examples on how to run basic benchmarks with the latest version of pytket. Please list the release version of pytket with any benchmarks you give, and feel free to get in touch for any assistance needed in setting up fair and representative tests.

User Support

If you have problems with the use of tket or you think that you have found a bug there are several ways to contact us:

  • You can join the tket-users mailing list. If you have questions or ideas and wishes for new features you can send an email to the list and ask for help. You can also join the list to get the newest information and get in contact with other users of tket.

  • Write an email to and ask for help with your problem.

  • You can write a bug report on the CQC github with details of the problem and we will pick that up. You can also have a look on that page so see if your problem has already been reported by someone else.

We are really thankful for all help to fix bugs in tket. Usually you will get an answer from someone in the development team of tket soon.


Copyright 2020-2021 Cambridge Quantum Computing

You may not use this product except in compliance with the Licence. You may view a copy of the Licence on the LICENCE page.

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