quantum-ts

TypeScript library for quantum computing: qubit math, state vectors, gates, and a circuit graph model.

AI Usage

AI has been partially used in this repos. Most of the documentation, including this readme, has been generated as well as most of Unit tests.

However, the library code has been written by hand. I created this repo to understand the math behind quantum computing, so there was no point in having a stochastic monkey copy/paste code it found on the internet.

Pull requests are wellcome, but no vibe code.

Installation

npm install @kissyagni/quantum-ts

Building the library

Requirements: Node.js 20 or later.

npm install
npm run build
npm test

Publishing the library

1. Bump the version in package.json (or use npm version patch|minor|major).
2. Build and test:

npm run build
npm test
npm login
npm publish --access public

Code samples

Manipulating single qubit

import { QBit } from '@kissyagni/quantum-ts';

// |0⟩ by default
const zero = new QBit();

// |1⟩ (θ = 180°)
const one = new QBit(180, 0);

// Bloch coordinates
const { x, y, z } = zero.toBlochXYZ(); // { x: 0, y: 0, z: 1 }

// From amplitudes α, β (must be normalized)
import * as math from 'mathjs';
const plus = QBit.fromAlphaBeta(
  math.complex(1 / math.SQRT2, 0),
  math.complex(1 / math.SQRT2, 0),
); // |+⟩

Manipulating Quantum State composed of several QBits

import { QBit, QState } from '@kissyagni/quantum-ts';

// Create state |+⟩ ⊗ |-⟩ 
const state = QState.createFromQBits([new QBit(90, 0), new QBit(-90, 0)]);

// Inspect the resulting state
state.pureness;
state.densityMatrix;
state.stateVector;

Building a circuit

import { QuantumCircuitGraph } from '@kissyagni/quantum-ts';

// 2 input qubits
const circuit = new QuantumCircuitGraph(2);

circuit.h(0);           // Hadamard on qubit 0
circuit.cnot(0, 1);     // CNOT: control 0, target 1

// Compute final quantum state of circuit
const finalState = new QState();
circuit.output.computeStateTo(finalState);

// get information of quantum state
finalState.pureness;
finalState.densityMatrix;
finalState.stateVector;

// Collapse the circuit into one unitary operator
const gate = circuit.toGate();