quantrs2

Facade crate for QuantRS2: unified entry point and documentation

This crate provides a single, convenient entry point that re-exports the public APIs from all QuantRS2 subcrates. Instead of managing multiple dependencies, you can simply add quantrs2 with the features you need.

Quick Start

Add this to your Cargo.toml:

[dependencies]
# Enable all features
quantrs2 = { version = "0.1.0-beta.1", features = ["full"] }

# Or select specific features
quantrs2 = { version = "0.1.0-beta.1", features = ["circuit", "sim"] }

Then use it in your code:

// With the facade crate, modules are available under quantrs2::
use quantrs2::core::api::prelude::essentials::*; // QubitId, Register, QuantRS2Result
use quantrs2::circuit::builder::{Circuit, Simulator}; // Circuit and the Simulator trait
use quantrs2::sim::statevector::StateVectorSimulator; // Feature "sim"

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Create a 2-qubit circuit (const-generic N)
    const N: usize = 2;
    let mut circuit = Circuit::<N>::new();
    circuit.h(QubitId::new(0))?;
    circuit.cx(QubitId::new(0), QubitId::new(1))?;

    // Simulate the circuit
    let mut simulator = StateVectorSimulator::new();
    let result: Register<N> = simulator.run(&circuit)?;

    println!("Measurement results: {:?}", result);
    Ok(())
}

Available Features

Module Structure

When you enable features, the corresponding modules become available:

// Core is always available
use quantrs2::core;

// Available with "circuit" feature
use quantrs2::circuit;

// Available with "sim" feature
use quantrs2::sim;

// Available with "anneal" feature
use quantrs2::anneal;

// Available with "device" feature
use quantrs2::device;

// Available with "ml" feature
use quantrs2::ml;

// Available with "tytan" feature
use quantrs2::tytan;

// Available with "symengine" feature
use quantrs2::symengine;

Feature Dependencies

Some features automatically enable others for convenience:

• sim → enables circuit
• anneal → enables circuit
• device → enables circuit
• ml → enables sim and anneal (which also enables circuit)
• tytan → enables anneal (which also enables circuit)

When to Use This Crate

Use quantrs2 when:

• You want a simple, unified dependency
• You're building applications that use multiple QuantRS2 components
• You prefer feature flags over managing multiple crate dependencies
• You want the convenience of a single import namespace

Use individual crates when:

• You only need specific functionality (e.g., just quantrs2-core)
• You want minimal compile times and dependencies
• You're building libraries that should have minimal dependencies
• You need fine-grained control over versions

Example Configurations

Minimal quantum programming:

quantrs2 = { version = "0.1.0-beta.1", features = ["circuit"] }

Circuit simulation:

quantrs2 = { version = "0.1.0-beta.1", features = ["sim"] }

Quantum machine learning:

quantrs2 = { version = "0.1.0-beta.1", features = ["ml"] }

Hardware interaction:

quantrs2 = { version = "0.1.0-beta.1", features = ["device", "sim"] }

Everything:

quantrs2 = { version = "0.1.0-beta.1", features = ["full"] }

Alternative: Individual Crates

If you prefer to use individual crates instead of the facade:

[dependencies]
quantrs2-core = "0.1.0-beta.1"
quantrs2-circuit = "0.1.0-beta.1"
quantrs2-sim = "0.1.0-beta.1"
# etc.

End-to-End Example

This example builds a Bell state on 2 qubits and prints the probabilities. Enable features circuit and sim.

use quantrs2::core::api::prelude::essentials::*;
use quantrs2::circuit::builder::{Circuit, Simulator};
use quantrs2::sim::statevector::StateVectorSimulator;

fn main() -> Result<(), Box<dyn std::error::Error>> {
    const N: usize = 2;
    let mut circuit = Circuit::<N>::new();
    circuit.h(QubitId::new(0))?;                  // H on qubit 0
    circuit.cx(QubitId::new(0), QubitId::new(1))?; // CNOT 0->1

    let sim = StateVectorSimulator::new();
    let reg: Register<N> = sim.run(&circuit)?;

    let probs = reg.probabilities();
    println!(
        "|00>: {:.3}, |01>: {:.3}, |10>: {:.3}, |11>: {:.3}",
        probs[0], probs[1], probs[2], probs[3]
    );
    Ok(())
}

Documentation

• Main QuantRS2 Documentation
• Examples and Tutorials

Subcrates

• quantrs2-core: Core types, math, error handling, and APIs — https://github.com/cool-japan/quantrs/tree/master/core
• quantrs2-circuit: Circuit builder, DSL, optimization — https://github.com/cool-japan/quantrs/tree/master/circuit
• quantrs2-sim: Simulators (statevector, stabilizer, MPS, etc.) — https://github.com/cool-japan/quantrs/tree/master/sim
• quantrs2-anneal: Quantum annealing algorithms and workflows — https://github.com/cool-japan/quantrs/tree/master/anneal
• quantrs2-device: Hardware/device connectors and scheduling — https://github.com/cool-japan/quantrs/tree/master/device
• quantrs2-ml: Quantum machine learning utilities — https://github.com/cool-japan/quantrs/tree/master/ml
• quantrs2-tytan: High-level annealing interface inspired by TYTAN — https://github.com/cool-japan/quantrs/tree/master/tytan
• quantrs2-symengine: Symbolic computation bindings — https://github.com/cool-japan/quantrs/tree/master/quantrs2-symengine

License

Licensed under either of

• Apache License, Version 2.0, (LICENSE-APACHE or http://www.apache.org/licenses/LICENSE-2.0)
• MIT license (LICENSE-MIT or http://opensource.org/licenses/MIT)

at your option.