OpenQASM

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Open Quantum Assembly Language (OpenQASM; pronounced open kazm^[1]) is an intermediate representation for quantum instructions. The language was first described in a paper published in July 2017,^[1] and a reference source code implementation was released as part of IBM's Quantum Information Software Kit (Qiskit) for use with their IBM Quantum Experience cloud quantum computing platform.^[2] The language has similar qualities to traditional hardware description languages such as Verilog.

OpenQASM defines its version at the head of a source file as a number, as in the declaration:

OPENQASM 3;

The level of OpenQASM's original published implementations is OpenQASM 2.0. Version 3.0 of the specification is the current one and can be viewed at the OpenQASM repository on GitHub.

Examples[]

The following is an example of OpenQASM source code from the official library. The program adds two four-bit numbers.^[3]

/*
 * quantum ripple-carry adder
 * Cuccaro et al, quant-ph/0410184
 */
OPENQASM 3;
include "stdgates.inc";

gate majority a, b, c {
    cx c, b;
    cx c, a;
    ccx a, b, c;
}

gate unmaj a, b, c {
    ccx a, b, c;
    cx c, a;
    cx a, b;
}

qubit[1] cin;
qubit[4] a;
qubit[4] b;
qubit[1] cout;
bit[5] ans;
uint[4] a_in = 1;  // a = 0001
uint[4] b_in = 15; // b = 1111
// initialize qubits
reset cin;
reset a;
reset b;
reset cout;

// set input states
for i in [0: 3] {
  if(bool(a_in[i])) x a[i];
  if(bool(b_in[i])) x b[i];
}
// add a to b, storing result in b
majority cin[0], b[0], a[0];
for i in [0: 2] { majority a[i], b[i + 1], a[i + 1]; }
cx a[3], cout[0];
for i in [2: -1: 0] { unmaj a[i],b[i+1],a[i+1]; }
unmaj cin[0], b[0], a[0];
measure b[0:3] -> ans[0:3];
measure cout[0] -> ans[4];

References[]

External links[]

• OpenQASM on GitHub