qiskit-omelyan 0.2.0

Omelyan-based product formulas for time evolution in Qiskit

qiskit-omelyan

Omelyan-type (and related) symmetric product formulas for Hamiltonian time evolution in Qiskit.

This project provides a general ramp-based construction, OmelyanTrotter, along with a collection of well-known optimized schemes from the literature. The goal is to give you more control over time-evolution circuit synthesis—especially when you want lower Trotter error at fixed (or comparable) gate depth than standard Suzuki–Trotter constructions.

The implementation integrates with Qiskit’s existing operator and synthesis stack:

• SparsePauliOp for representing Hamiltonians
• PauliEvolutionGate for defining time evolution
• ProductFormula-style synthesis to generate circuits

Features

OmelyanTrotter (general framework)

OmelyanTrotter is a symmetric product-formula constructor (subclassing Qiskit’s ProductFormula) based on ramp notation. It supports:

• even orders (order)
• cycles (cycles)
• symmetric parameter vectors (c_vec)
• multiple steps (reps)
• optional circuit optimizations:
  • merging consecutive identical single-qubit rotations (merge_single)
  • merging boundaries between consecutive steps (merge_steps)

This makes it possible to implement a broad family of symmetric product formulas in a uniform way and to reproduce known optimized schemes from the literature.

Built-in schemes

This repository includes ready-to-use schemes implemented as subclasses/instances of OmelyanTrotter, including:

• 2nd order: Leapfrog2, Omelyan2
• 4th order: Forest_Ruth4, Omelyan4, Malezic_Ostmeyer4
• 6th order: Yoshida6, Blanes_Moan6, Malezic_Ostmeyer6
• 8th / 10th order: Morales8, Morales10

Collection of schemes

All top most efficient schemes at orders $n = 2, 4, 6$ are collected in the repository: https://github.com/MarkoMalezic/efficient-trotterizations. These are based on the paper by Malezic & Ostmeyer (arXiv: 2601.18756)

Installation

From PyPI

pip install "qiskit-omelyan"

With example dependencies

pip install "qiskit-omelyan[examples]"

From GitHub (latest main)

pip install "qiskit-omelyan @ git+https://github.com/MarkoMalezic/qiskit-omelyan.git"

With example dependencies:

pip install "qiskit-omelyan[examples] @ git+https://github.com/MarkoMalezic/qiskit-omelyan.git"

Quick start

Minimal example (Hamiltonian as SparsePauliOp):

from qiskit.circuit.library import PauliEvolutionGate
from qiskit.quantum_info import SparsePauliOp

from qiskit_omelyan import OmelyanTrotter, Omelyan2  # or any other scheme

t = 1.0

H = SparsePauliOp.from_list([
    ("ZI", 1.0),
    ("IZ", 1.0),
    ("XX", 0.5),
])

evolution = PauliEvolutionGate(H, time=t)

# Option 1: use a ready-to-use scheme
synth = Omelyan2(reps=50, merge_single=True, merge_steps=True)
qc = synth.synthesize(evolution)

# Option 2: construct a custom OmelyanTrotter
# qc = OmelyanTrotter(order=2, cycles=1, c_vec=[...], reps=50).synthesize(evolution)

print(qc)

Examples

See examples/ and examples/README.md.

Typical usage:

cd examples
python leapfrog2_circuit.py
python omelyan2.py

Some examples compare against exact statevector evolution for small systems using scipy.linalg.expm, so keep the number of qubits small.

Validation / comparison

The schemes in this repository are designed to be comparable to existing Qiskit synthesis methods such as SuzukiTrotter (and, in a different regime, QDrift). For small systems, you can validate correctness by comparing against exact matrix exponentiation and evaluating fidelity/error.

References

• I. Omelyan, I. Mryglod and R. Folk, Optimized Forest–Ruth- and Suzuki-like Algorithms for Integration of Motion in Many-body Systems (2002)
• N. Hatano and M. Suzuki, Finding Exponential Product Formulas of Higher Orders (2005)
• H. Yoshida, Construction of higher order symplectic integrators (1990)
• L. Verlet, Computer "Experiments" on Classical Fluids (1967)
• E. Forest and R. D. Ruth, Fourth-order Symplectic Integration (1990)
• S. Blanes and P. Moan, Practical Symplectic Partitioned Runge–Kutta and Runge–Kutta–Nyström Methods (2002)
• M. E. S. Morales, P. C. S. Costa, D. K. Burgarth, Y. R. Sanders, Greatly improved higher-order product formulae for quantum simulation (2022)
• J. Ostmeyer, Optimised Trotter decompositions for Classical and Quantum Computing (2023)
• M. Maležič and J. Ostmeyer, Efficient Trotter–Suzuki Schemes for Long-Time Quantum Dynamics (2026)

License

Apache License 2.0 — see LICENSE.