QuantRS2 0.1.1 Released — Clean Builds Across Every Feature Flag

Ship the framework, then tighten the bolts.

Today we released QuantRS2 0.1.1 — a same-day patch that makes the modular quantum framework build cleanly in every feature configuration.

QuantRS2 (/kwɒntərz tu:/) is a comprehensive, pure-Rust quantum computing framework: simulation, algorithm development, and hardware interaction. No C. No Fortran. No CUDA toolkit. No Python runtime. Where the incumbents lean on Qiskit, Cirq, Stim, and cuQuantum, QuantRS2 compiles down to a single static binary — and to WASM when you want quantum circuits in the browser.

This is the first patch after the 0.1.0 debut, shipped the same day. Nothing glamorous: it is a build-hygiene release. But for a workspace this modular, build hygiene is a feature.

Why 0.1.1 matters

QuantRS2 is built so you enable only the backends you actually need. Targeting IBM Quantum? Turn on the IBM client. Running on Azure Quantum, AWS Braket, or D-Wave? Flip those features instead. Doing photonic work? There’s a module for that too. Most users never need all of them at once, and the design respects that.

The trade-off with a feature matrix that large is that some combinations slip through at launch. A few of ours did. 0.1.1 hardens the conditional compilation so a minimal feature set — or any subset — compiles without errors. Concretely:

• The device crate was missing a #[cfg(feature = "photonic")] guard on its photonic module re-exports. Now it’s gated correctly.
• The cross-platform and cloud benchmarking paths had conditional-compilation gaps for the aws, azure, and ibm cloud-client imports and struct fields. Fixed.
• With cloud-provider features disabled, the workspace now builds cleanly — no compile errors on a minimal default feature set.

If you only want a state-vector simulator and a circuit builder, you should never pay for a cloud SDK you didn’t ask for. After 0.1.1, you don’t.

Getting Started

Add the core trio:

cargo add quantrs2-core quantrs2-circuit quantrs2-sim

Then build a Bell state and run it on the state-vector simulator:

use quantrs2_circuit::builder::Circuit;
use quantrs2_sim::statevector::StateVectorSimulator;

fn main() {
    // Create a circuit with 2 qubits
    let mut circuit = Circuit::<2>::new();

    // Build a Bell state circuit: H(0) followed by CNOT(0, 1)
    circuit.h(0).unwrap()
           .cnot(0, 1).unwrap();

    // Run the circuit on the state vector simulator
    let simulator = StateVectorSimulator::new();
    let result = circuit.run(simulator).unwrap();

    for (i, prob) in result.probabilities().iter().enumerate() {
        let bits = format!("{:02b}", i);
        println!("|{}⟩: {:.6}", bits, prob);
    }
}

Add quantrs2-device only when you’re ready to target real hardware — that’s where the IBM, Azure, AWS, and D-Wave backends live.

What’s New in 0.1.1

Fixed

• Device crate: added the missing #[cfg(feature = "photonic")] guard on photonic module re-exports.
• Cloud benchmarking: fixed conditional compilation for the aws, azure, and ibm cloud-client imports and struct fields.
• Feature gating: the workspace now builds cleanly with cloud-provider features disabled — no compile errors with a minimal default feature set.

Changed

• All workspace crate versions bumped 0.1.0 → 0.1.1.
• Workspace dependencies updated to use 0.1.1.

No new algorithms, no API changes, no benchmark changes. Just a framework that compiles in every shape you ask of it.

Tips

• Keep your default feature set minimal. Add backend features (device, ibm, photonic, and friends) only when you actually need them. Smaller builds, faster compiles.

• Compose with the meta-crate. The quantrs2 crate exposes feature flags circuit, sim, anneal, device, ml, tytan, symengine, and full, so you assemble exactly the stack you want and nothing more.

• Catch gating regressions in CI. Build with --no-default-features plus each backend feature individually:

  cargo build --no-default-features --features sim
  cargo build --no-default-features --features device
  

  This is exactly the class of slip 0.1.1 fixes — testing the subsets keeps it from coming back.

• Upgrading from 0.1.0 is a drop-in version bump. No code changes required; just point your dependencies at 0.1.1.

Built on SciRS2

QuantRS2 rides on the SciRS2 ecosystem (v0.1.2) for its numerical foundation — arrays, linear algebra, parallelism, and GPU support via scirs2-core — alongside NumRS2, OptiRS, and Oxicode in the young, pure-Rust COOLJAPAN stack. It’s early days, and the foundation is growing fast.

Repository: https://github.com/cool-japan/quantrs

Star the repo if a sovereign, pure-Rust quantum stack is something you want to see grow.

Pure Rust quantum computing is here — fast, safe, and sovereign.

— KitaSan at COOLJAPAN OÜ January 21, 2026