Pipeline

A Pipeline is a structured wrapper around a circuit that separates three concerns into distinct stages: input preparation, core algorithm, and output measurement. It's the recommended way to organize non-trivial circuits.

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

const job = pipeline(
  { qubits: 3 },          // Circuit config
  "101",                   // Input stage
  Q => Q.all().measure(),  // Output stage
  Q => {                   // Algorithm stage
    Q.comment("Core algorithm");
    Q.bit(0).cx(Q.bit(1));
  }
);

const qasm = job.compile();

Stage Order

Stages execute in this order regardless of argument position:

1. Input — state initialization (input() is called for you)
2. Algorithm — your core gates callback
3. Output — measurement / post-processing

Input Stage

Accepts the same values as circuit.input():

// Binary string
pipeline({ qubits: 3 }, "101", output, algorithm);

// Pauli string
pipeline({ qubits: 3 }, "XZI", output, algorithm);

// Gate array
pipeline({ qubits: 3 }, ['H', 'X', '0'], output, algorithm);

// Endian option
pipeline({ qubits: 3 }, { source: "101", endian: 'little' }, output, algorithm);

// Callback
pipeline({ qubits: 3 }, Q => { Q.bit(0).h(); }, output, algorithm);

Output Stage

Accepts a function or a structured object:

// Function
pipeline({ qubits: 2 }, input, Q => Q.all().measure(), algorithm);

// Structured with format shorthand
pipeline({ qubits: 2 }, input, { format: 'readEach' }, algorithm);
// readEach: Q.all().measure()
// readToOne: Q.first().measure()

// With post-processing
pipeline({ qubits: 2 }, input, {
  format: 'readEach',
  postProcess: results => {
    return Object.entries(results).sort((a, b) => b[1] - a[1]);
  }
}, algorithm);

Compiling

const qasm3 = job.compile();
const qasm2 = job.compile({ version: '2.0' });

Running with a Simulator

The run() method accepts any simulator that implements the quantum-circuit interface (e.g. the quantum-circuit package):

import QuantumCircuit from 'quantum-circuit';

const sim = new QuantumCircuit();
const results = job.run(sim);

Internally, run() compiles to OpenQASM 2.0 (for maximum simulator compatibility), imports it, runs the simulation, and returns probabilities. If a postProcess callback was provided, its return value is used instead.

Accessing the Raw Circuit

const c = job.rawCircuit; // Returns the underlying Circuit instance