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Gate and operation specification for quantum circuits

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OpenQASM is an imperative programming language for describing quantum circuits. It is capable to describe universal quantum computing using the circuit model, measurement-based model, and near-term quantum computing experiments.

Specs, examples and tools for the OpenQASM intermediate representation.

Current version: 3.0

Live doc: version 3.0

For previous version see: 2.0

About this project

On this repository, you'll find all the documentation related to OpenQASM and some useful OpenQASM examples.

Language specs

The live language documentation specification.


The examples can be found under the examples folder.

They are OpenQASM files, i.e.:

 * Repeat-until-success circuit for Rz(theta),
 * cos(theta-pi)=3/5, from Nielsen and Chuang, Chapter 4.
include "";


  • Applies identity if out is 01, 10, or 11 and a Z-rotation by
  • theta + pi where cos(theta)=3/5 if out is 00.
  • The 00 outcome occurs with probability 5/8.
  • / def segment qubit[2]:anc, qubit:psi -> bit[2] { bit[2] b; reset anc; h anc; ccx anc[0], anc[1], psi; s psi; ccx anc[0], anc[1], psi; z psi; h anc; measure anc -> b; return b; }

qubit input; qubit ancilla[2]; bit flags[2] = "11"; bit output;

reset input; h input;

// braces are optional in this case while(int(flags) != 0) { flags = segment ancilla, input; } rz(pi - arccos(3 / 5)) input; h input; output = measure input; // should get zero

Citation format

For research papers, we encourage authors to reference.

  • Andrew W. Cross, Lev S. Bishop, John A. Smolin, Jay M. Gambetta "Open Quantum Assembly Language" [arXiv:1707.03429].


This project is licensed under the Apache License 2.0 - see the [LICENSE] file for details.


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