OpenQASM

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

This repo contains the OpenQASM specification, examples, and tools for the OpenQASM intermediate representation.

OpenQASM is a Qiskit project.

Examples

An example of OpenQASM 2.0 source code is given below. Several more examples may be found in the examples folder.

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

/*
 * 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[2] ancilla;
bit[2] flags = "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
Translation
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Simulation
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Citation format

For research papers, we encourage authors to reference.

• [Version 3.0] Andrew W. Cross, Ali Javadi-Abhari, Thomas Alexander, Niel de Beaudrap, Lev S. Bishop, Steven Heidel, Colm A. Ryan, John Smolin, Jay M. Gambetta, Blake R. Johnson "OpenQASM 3: A broader and deeper quantum assembly language" [arxiv:2104.14722].
• [Previous Version: 2.0] Andrew W. Cross, Lev S. Bishop, John A. Smolin, Jay M. Gambetta "Open Quantum Assembly Language" [arXiv:1707.03429].