Is there a way to visualize the Bloch sphere using Cirq, ProjectQ, and/or PyQuil, as it is possible using plot_bloch_vector in Qiskit?


1 Answer 1


The answer seems to be "no" for all three. From what I can find, Cirq and PyQuil default to QuTiP for Bloch sphere visualization, and ProjectQ does not have any examples to go off of, nor can I find the functionality in their GitHub.

  • TensorFlow Quantum, which primarily uses Cirq (since they are both owned by Google), used qutip.Bloch in this binary classification tutorial instead of any Cirq function, implying that Cirq does not have an equivalent.
  • Rigetti, which owns PyQuil, used qutip.Bloch in this training material instead of any PyQuil function, and in this intro tutorial, implying that PyQuil does not have an equivalent.
  • ProjectQ does not have any publicly visible Bloch sphere visualization tools in their Github, either. But their software already uses the IBM quantum experience, so I believe they would default to qiskit.plot_bloch_vector.

These are my findings based on briefly poking around in each of these softwares’ open-source. If there are any Cirq/ProjectQ/PyQuil contributors out there, please correct me if I am wrong.

  • 4
    $\begingroup$ Cirq maintainer here: yes, Cirq currently does not have a Bloch sphere plot but we are aiming to implement one in the coming months. You can use cirq.bloch_vector_from_state_vector to calculate the bloch vector for a given qubit in a given state though. $\endgroup$ Commented Apr 28, 2021 at 21:14
  • $\begingroup$ Thank you for your answers! $\endgroup$ Commented Apr 28, 2021 at 21:32

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