Changelog

All notable changes to this project will be documented in this file.

The format is based on a mixture of Keep a Changelog and Common Changelog. This project adheres to Semantic Versioning, with the exception that minor releases may include breaking changes.

Unreleased

Added

• extended EquivalenceChecker output to include entropy and the resulting diff data structure (#364) (@yiranwang-phys)

• OpenQASM2 and 3 files can now be read directly by the Simulator and EquivalenceChecker (#464) (@Marerido)

• improved Qiskit gate compatibility with matrix fallback (#464) (@aaronleesander)

• added MPO zip-up as default long-range gate application method (#449) (@aaronleesander)

• parallelized MPO equivalence checker (#448) (@aaronleesander)

• added tebd/hybrid/tdvp options for circuit simulation (#441) (@aaronleesander)

• added Krylov tolerance as high-level parameter (#439) (@aaronleesander)

• added accuracy presets to simulation parameters (#438) (@aaronleesander)

• added Simulator class that owns execution-side configuration and dispatches to all simulation backends, and a Result dataclass returned by Simulator.run (#430) (@aaronleesander)

• added linalg submodule to open a new path for optimizations and stop BLAS thread oversubscription for stability (#429) (@aaronleesander)

• added high-level State and Hamiltonian classes at user-facing level (#426) (@aaronleesander)

• added Fermionic and Jordan-Wigner MPO encodings of 1D Fermi-Hubbard model (#220) (@thilomueller)

• added deterministic ensemble evolution with optional autocorrelator and two-time correlator outputs, including periodic-wrap two-site observable support on (L-1, 0) (#409) (@Gauthameshwar)

Changed

• simplified user-facing top-level imports (#467) (@aaronleesander)

• updated documentation structure and content (#465) (@aaronleesander)

• changed analog simulation default mode to 2TDVP (#458) (@aaronleesander)

• overhauled TDVP backend (#457) (@aaronleesander)

• changed default to TEBD in digital circuit simulation (#445) (@aaronleesander)

• refactored public API to use Simulator, Result, and EquivalenceChecker classes (#430) (@aaronleesander)

• sped up and stabilized test suite (#428) (@aaronleesander)

• changed simulator.run to accept State | list[State] and Hamiltonian for analog simulations instead of MPS / MPO (#422) (@aaronleesander)

• changed solver to representation and updated noise-free simulation paths (#422) (@aaronleesander)

Removed

• removed the free mqt.yaqs.simulator.run function; call sites must migrate to Simulator(...).run(...) (#430) (@aaronleesander)

• removed show_progress and (unused) num_threads keyword arguments from AnalogSimParams, StrongSimParams, and WeakSimParams; pass show_progress to Simulator instead (#430) (@aaronleesander)

Fixed

• fixed NoiseModel factor order when two-site indices are normalized (#396) (@aleramos119)

• refactored observable handling in simulator to preserve user order (#447) (@aaronleesander)

• added tests to ensure qubit ordering matches Qiskit (#446) (@aaronleesander)

• minor cleanup (#420) (@aaronleesander)

0.5.0 - 2026-05-12

Added

• added MPS(..., state="haar-random") initializer using Haar-random isometries with optional bond-dimension cap via pad (#400) (@Gauthameshwar)

• added process tomography for non-Markovian noise (#344) (@aaronleesander)

• added ability to measure in X or Y basis (#339) (@aaronleesander)

• added Arnoldi iteration as alternative to Lanczos method (#338) (@aaronleesander)

• added Monte Carlo Wavefunction solver (#333) (@aaronleesander)

• added MPO.from_matrix() method (#331) (@lucello)

• added Lindblad solver for small systems (#330) (@aaronleesander)

• Noise model strengths can now be sampled from a normal distribution (#329) (@aaronleesander)

Changed

• changed Lindblad and MCWF solvers to use sparse implementation (#338) (@aaronleesander)

Fixed

• fixed numba attempting to parallelize in already parallelized processes (#337) (@aaronleesander)

• fixed potential memory leak in parallelization (#336) (@aaronleesander)

0.4.0 - 2026-02-05

Added

• added ability to schedule jumps (#319) (@aaronleesander)

• added Bose-Hubbard Hamiltonian option (#309) (@lucello)

• added multi-threading setting for noise-free ones (#316) (@aaronleesander)

• Minor improvements to TDVP performance (#311) (@aaronleesander)

• ⚡️ Improve Lanczos iteration and use numba for significant speedup (#310) (@aaronleesander)

Changed

• ♻️ Change Pauli summation to use finite state machine construction (#308) (@aaronleesander)

• 🔧 Replace mypy with ty (#304) (@denialhaag)

Removed

• 👷‍♂️ Stop testing on x86 macOS systems (#310) (@aaronleesander)

0.3.3 - 2026-01-12

Added

• updated bib and readme with Nature Communications publication (#298) (@aaronleesander)

• updates MPO class to allow construction of arbitrary Pauli Hamiltonians (#216) ([@aaronleesander, @thilomueller])

• added faster paths for TDVP dense effective Hamiltonian (#280) (@aaronleesander)

• added more stable and faster SVD and QR implementation (#278) (@aaronleesander)

• TDVP now utilizes a dense Hamiltonian for small tensor sizes (adjusted by global variable DENSE_THRESHOLD) (#261) (@aaronleesander)

• Updated readability of TDVP subfunctions and Lanczos method (#261) (@aaronleesander)

Fixed

• Fixed bug where two-site dissipative processes were computed in loop (#290) (@aaronleesander)

• Fixed a truncation bug in TDVP sometimes leading to over-truncation (#274) (@aaronleesander)

• Updated Lanczos method’s vdot order to match mathematical expectations (#261) (@aaronleesander)

0.3.2 - 2025-10-16

If you are upgrading: please see UPGRADING.md.

Added

• ✨ Make it possible to return final state without setting dummy observables (#214) (@aaronleesander)

• 👷 Enable testing on Python 3.14 (#212) (@denialhaag)

Removed

• 🔥 Drop support for Python 3.9 (#180) (@denialhaag)

Fixed

• 🐛 Fix project bar of simulator (#213) (@aaronleesander)

0.3.1 - 2025-08-29

📚 Refer to the GitHub Release Notes for previous changelogs.