Release News: Qiskit v2.5 is here!
IBM has released Qiskit SDK v2.5, introducing performance improvements and new compiler tools for quantum developers. This update focuses on programmable performance, allowing users to build custom compilation pipelines that better match their specific research or application needs. A significant addition is the multi-representation compiler framework, which enables developers to manage complex workflows that move between different intermediate representations.
For those working with fault-tolerant quantum computing, the release includes dedicated pass managers for both Pauli-based computation and Clifford plus T representations. These tools provide pre-built, configurable pipelines that simplify the process of targeting specific quantum architectures. The update also improves the transpiler stack, with enhancements to the LightSabre routing algorithm and increased use of multithreading to speed up compilation times across the board.
Another key change is the introduction of a fidelity-focused optimization pass, which uses hardware error data to guide circuit synthesis. By prioritizing execution fidelity over raw gate count, this pass helps programs perform better on real quantum hardware. Additionally, the C API now supports full inspection of classical control flow, filling a major functional gap for low-level tooling.
Alongside these technical changes, IBM has updated the naming of its services. The Qiskit Runtime Service is now the IBM Quantum Compute Service. This change is intended to distinguish the open-source software development kit from the managed cloud service used for executing quantum workloads. There are no changes to existing APIs or workflows resulting from this naming update.
Users should note that Qiskit v2.5 requires NumPy 2.0 and SciPy 1.14 or later. Extensions compiled against previous versions of the C API will likely require a rebuild to maintain compatibility with this release. Those still using the v1.x series should upgrade as soon as possible, as that series reached its end of life earlier this summer.