everett

A clean, zero-dependency statevector quantum simulator in Rust.

everett represents the quantum state of n qubits as a complex vector of dimension 2^n and applies gates in place over amplitude index-groups, never by materializing a 2^n x 2^n matrix. The name is a nod to the many-worlds interpretation: a statevector holds the entire branching wavefunction at once.

Example

use everett::prelude::*;

// prepare a Bell state: (|00> + |11>) / sqrt(2)
let mut circuit = Circuit::new(2);
circuit.h(0).cnot(0, 1);

let state = StateVectorBackend::run(&circuit)?;
assert!((state.probability(0b00) - 0.5).abs() < 1e-12);
assert!((state.probability(0b11) - 0.5).abs() < 1e-12);
# Ok::<(), everett::Error>(())

What's included (v1)

• A universal gate set (H, X, Y, Z, S, T, rotations, phase) plus two-qubit gates (CNOT, CZ, SWAP) and arbitrary controlled gates.
• Projective measurement with Born-rule sampling and mid-circuit, classically-controlled operations.
• Worked algorithms: Bell/GHZ state preparation, teleportation, superdense coding, the quantum Fourier transform, phase estimation, and Hamiltonian simulation via Trotterization.

Development

This project uses Nix flakes. The default shell provides the stable toolchain; separate shells provide the nightly toolchain for Miri and the Kani verifier.

nix develop            # stable toolchain + rust-analyzer
nix flake check        # build, clippy, fmt, tests, doctests

nix develop .#miri     # nightly + miri, for undefined-behavior checking
nix develop .#kani     # kani, for bounded formal verification

Without Nix, a standard cargo toolchain (1.95+) works for everything except the Miri and Kani steps.

License

Licensed under either of Apache License, Version 2.0 or MIT license at your option.