Show HN: Ket – quantum circuit simulator, TypeScript, 3 back ends, 14 formats

I built a quantum circuit simulator that runs entirely in Node.js or the browser with no Python dependency.

The core problem: every serious quantum tool requires Python. If you're building a web app, an educational tool, or just want to work in TypeScript, you're stuck either shelling out to Python or using libraries that are years stale.

Three simulation backends in one library: - Statevector — sparse Map<bigint, Complex>, practical to ~20 qubits - MPS/tensor network — O(n·χ²) memory, runs GHZ-100 in 30ms - Exact density matrix — per-gate depolarizing noise, no Monte Carlo

14 import/export formats — OpenQASM 2/3, Qiskit Python, Cirq, IonQ JSON, Quil, Q#, pyQuil, Braket, CudaQ, TFQ, Quirk, LaTeX, native JSON. Round-trips its own format losslessly.

IonQ hardware targeting — validate circuits against real device specs (aria-1, forte-1, harmony) before submitting. Published noise figures built in.

717 tests covering analytic correctness, gate invertibility, BigInt correctness at qubit indices 30/31/40, and full round-trips for all formats.

npm install @kirkelliott/ket

GitHub: https://github.com/dmvjs/ket