5. What’s New in Qiskit 2.x[4]

In 2025, Qiskit has officially moved into its 2.x era. While the overall direction from the 1.x series remains, this new release brings a host of improvements that make life easier for quantum developers. Let’s walk through the highlights.

A Simpler Package Structure

With Qiskit 2.x, you only need to install the Qiskit metapackage—everything you need comes bundled in one place. You no longer have to manage qiskit-terra or qiskit-aer separately, which means fewer headaches with dependencies.

Stable, Compatible APIs

Qiskit 2.x follows semantic versioning, giving developers confidence about compatibility:

Major versions (2.x → 3.x): may include breaking changes

Minor versions (2.1 → 2.2): introduce new features

Patch versions (2.1.0 → 2.1.1): fix bugs

This makes it easier to plan long-term projects without fear of sudden disruptions.

Faster with Rust

Parts of the transpiler have been rewritten in Rust, delivering around 20% performance improvements. For researchers handling large circuits, this is a significant speed boost.

Smarter Primitives API

The Primitives API—the building blocks of quantum computing—has been expanded with more flexible input and output options. This makes it easier to design and customize experiments.

Expanded Authentication and Services

Cloud integration has become more flexible, with multiple authentication channels now available. A new local mode also lets you run primitives (like Sampler and Estimator) directly on local simulators such as AerSimulator.

ibm-quantum-platform – the newest channel, used by default in modern Qiskit Runtime

ibm-cloud – still available, but gradually being replaced by ibm_quantum_platform

ibm-quantum – deprecated and removed in recent Runtime versions (e.g., v0.40.0+)

Local – for running primitives on your own machine with simulators

More Powerful Simulator API

The simulator API has been upgraded with better performance and richer options, making trial-and-error experimentation much smoother.

Stronger OpenQASM Support

Control flow in OpenQASM has been enhanced, allowing for more expressive circuit descriptions.

C/C++ API Support

Until now, Qiskit was primarily Python-based. With 2.x, developers can now use C and C++ to build circuits, configure targets, and even work with new features like SparseObservable. Integration between C and Python is also supported.

Smarter Transpilation Optimizations

If your circuit is expressed in the Clifford+T basis, Qiskit automatically applies optimized transpilation paths, delivering faster results with hardware-friendly circuits.

Python 3.9 Deprecated

One note of caution: starting from Qiskit 2.3, Python 3.9 is no longer supported. You’ll need Python 3.10 or later.

Wrapping Up

Qiskit 2.x represents an evolution that keeps ease of use while boosting performance and flexibility. From Rust-based acceleration to C/C++ support, it’s designed to widen the scope of who can work with quantum computing.
Whether you’re just getting started or already deep into development, the latest Qiskit is worth exploring.

[4] Qiskit 2.0 Release Summary（IBM Quantum Blog）
https://www.ibm.com/quantum/blog/qiskit-2-0-release-summary