Pauliz

A high-performance, zero-dependency quantum computing simulation library written in Zig.

Features

• Pure Zig Implementation: No external dependencies; built entirely from the Zig Standard Library
• Compile-Time Generics: Fixed qubit counts enable aggressive compiler optimizations (loop unrolling, SIMD vectorization)
• Explicit Memory Management: Allocator-aware design for predictable resource utilization
• OpenQASM 2.0 Support: Full parse/export round-trip capability
• Noise Simulation: Monte Carlo wave function trajectories for realistic device modeling
• Neurosymbolic Verification: Dual symbolic/numerical testing framework

Quick Start

Requirements

• Zig 0.13.0 or later

Building

# Run tests
zig build test

# Run Bell state example
zig build bell

Usage

const pauliz = @import("pauliz");

// Create a 2-qubit circuit
var circuit = pauliz.Circuit(2, f64).init(allocator);
defer circuit.deinit();

// Build a Bell state: |00⟩ → (|00⟩ + |11⟩)/√2
_ = circuit.h(0).cnot(0, 1);

// Check probabilities
const p00 = circuit.probability(0);  // ~0.5
const p11 = circuit.probability(3);  // ~0.5

Architecture

src/
├── pauliz.zig          # Public API and re-exports
├── core/
│   ├── complex.zig     # Complex number arithmetic
│   └── state.zig       # Quantum state vector representation
├── gates/
│   ├── single.zig      # Single-qubit gates (H, X, Y, Z, S, T, Rx, Ry, Rz)
│   └── controlled.zig  # Multi-qubit gates (CNOT, CZ, SWAP, Toffoli)
├── circuit/
│   └── builder.zig     # Fluent circuit builder API
├── qasm/
│   ├── lexer.zig       # OpenQASM tokenizer
│   ├── parser.zig      # OpenQASM parser
│   └── exporter.zig    # QASM code generation
├── noise/
│   └── channels.zig    # Noise channels (bit flip, phase flip, amplitude damping)
└── viz/
    └── ascii.zig       # ASCII circuit visualization

Supported Gates

Single-Qubit Gates

Gate	Description
I	Identity
X	Pauli-X (NOT)
Y	Pauli-Y
Z	Pauli-Z
H	Hadamard
S	Phase gate (√Z)
T	π/8 gate (√S)
Rx(θ)	X-axis rotation
Ry(θ)	Y-axis rotation
Rz(θ)	Z-axis rotation

Multi-Qubit Gates

Gate	Description
CNOT	Controlled-NOT
CY	Controlled-Y
CZ	Controlled-Z
CH	Controlled-Hadamard
SWAP	Qubit swap
CCX	Toffoli (Controlled-Controlled-X)

Noise Channels

Monte Carlo wave function simulation supports:

• Bit Flip: X error with probability p
• Phase Flip: Z error with probability p
• Depolarizing: Random Pauli error
• Amplitude Damping: Energy relaxation (T₁ decay)
• Phase Damping: Dephasing (T₂ relaxation)

OpenQASM Example

const pauliz = @import("pauliz");

// Parse QASM
const source = "OPENQASM 2.0; qreg q[2]; h q[0]; cx q[0],q[1];";
var circuit = pauliz.Circuit(2, f64).init(allocator);
defer circuit.deinit();

var parser = pauliz.Parser(2, f64).init(allocator, source, &circuit);
try parser.parse();

// Export back to QASM
const qasm_code = try pauliz.exportToQasm(allocator, 2, f64, &circuit);
defer allocator.free(qasm_code);

Testing

The library employs a neurosymbolic verification approach:

# Run all tests (unit + integration)
zig build test

Tests verify:

• Algebraic identities: H·H = I, X·X = I, i² = -1
• Gate unitarity: U†U = I for all gates
• State normalization: ⟨ψ|ψ⟩ = 1
• QASM round-trip correctness

Research Paper

See paper/ for the accompanying Physical Review Letters-style research paper detailing the architecture, implementation, and validation methodology.

License

MIT License. See LICENSE for details.

Citation

@software{pauliz,
  author = {Kataru, Baalateja},
  title = {pauliz: Zero-Dependency Quantum Computing Simulation in Zig},
  year = {2026},
  publisher = {GitHub},
  url = {https://github.com/planckeon/pauliz}
}