Circuits

A circuit is the top-level container for your quantum program. You create one with the circuit() function, passing a config object and a builder callback.

import { circuit } from '@quantum-js/dsl';

const c = circuit({ qubits: 2 }, Q => {
  Q.bit(0).h();
  Q.bit(0).cx(Q.bit(1));
  Q.all().measure();
});

Configuration

interface CircuitConfig {
  qubits: number;   // Number of qubits (required)
  bits?: number;    // Classical register size (default: 1, grows on demand)
  version?: string; // QASM version: '3.0' (default) or '2.0'
}

The classical register grows automatically as you add measurements — you rarely need to set bits manually.

Compiling

Call .compile() on the returned circuit to get the QASM string:

const qasm3 = c.compile();              // OpenQASM 3.0 (default)
const qasm2 = c.compile({ version: '2.0' }); // OpenQASM 2.0 compatibility

Barriers and Comments

Use barriers to separate stages of your circuit visually and logically. Use comments for annotation and brk() for blank line spacing in the output.

circuit({ qubits: 3 }, Q => {
  Q.comment("State preparation");
  Q.input("101");
  Q.barrier();          // barrier across all qubits
  Q.brk();              // blank line in QASM output
  Q.comment("Algorithm");
  Q.bit(0).h();
});

Looping

Use loop() to repeat a block of operations a fixed number of times:

circuit({ qubits: 1 }, Q => {
  Q.loop(3, q => {
    q.bit(0).h().z();
  });
});