---
id: openfermion
version: "1.8.1"
license: Apache-2.0
license_treatment: permissive
maintenance: active
---

# openfermion — Package to compile and analyze quantum algorithms for simulating fermionic systems.

License: permissive · Maintenance: active · Downloads: 210.2K/mo

## What it is and what it does

OpenFermion is a Python package for quantum chemistry and fermionic system simulation on quantum computers. It provides data structures and algorithms to compile quantum circuits and analyze fermionic Hamiltonians, with built-in support for converting between fermionic and qubit representations. The package depends on cirq-core for quantum circuit operations, numpy and scipy for numerical computation, sympy for symbolic algebra, networkx for graph operations, and h5py for data I/O, plus pubchempy and requests for chemistry data retrieval.

The package is designed for researchers and developers working on quantum algorithms for electronic structure problems. It integrates with external plugins for high-performance simulation (OpenFermion-FQE), circuit compilation (Forest-OpenFermion, SFOpenBoson), and classical electronic structure packages (Psi4, PySCF, DIRAC, Q-Chem). Installation is straightforward via pip, though some plugins require Mac or Linux.

Use it for:

- Compile quantum circuits for simulating molecular electronic structure on quantum computers
- Convert fermionic Hamiltonians to qubit representations for NISQ devices
- Analyze and manipulate fermionic operators for quantum chemistry research
- Integrate quantum simulations with classical electronic structure packages via plugins
- Develop and test quantum algorithms for chemistry applications

## Worth the install?

AI-flagged interpretation of the facts above — verify before relying.

OpenFermion compiles and analyzes quantum algorithms to simulate fermionic systems, providing data structures and tools for manipulating fermionic and qubit Hamiltonians for quantum chemistry applications.

Yes. OpenFermion is actively maintained, has low install friction, carries no known vulnerabilities, and is licensed permissively. Install it if you are developing quantum algorithms for chemistry or fermionic systems. The main constraint is Python version (≥3.10) and platform support for certain plugins (Mac/Linux preferred for electronic structure integration).

## Install

pip install openfermion
uv add openfermion
poetry add openfermion

## Installing openfermion

Before you install: Low install friction with a pure-Python wheel distribution. Active maintenance with a release within 28 days. Supports current Python versions (3.10–3.13) and runs on Mac, Windows, and Linux.

License in practice: Licensed under Apache-2.0 (permissive). You may use, modify, and distribute the package freely in commercial and private projects, provided you retain the license notice.

Quickstart:

pip install openfermion

import openfermion
# Create and manipulate fermionic operators
operator = openfermion.FermionOperator('0^ 1')

Requires Python >= 3.10.0. Electronic structure plugins are only compatible on Mac and Linux; Windows users may use Docker.

Verify before relying:

- Whether the package's quantum simulation capabilities are suitable for your specific fermionic system or chemistry problem scale
- Performance characteristics and memory requirements for large Hamiltonian representations
- Integration requirements with specific quantum hardware or simulators beyond those mentioned in the description

## Package facts

- License: Apache-2.0 (permissive)
- Python support: supports_current
- Install friction: low
- Maintenance: active
- Downloads: 210.2K/month (top 15,000 on PyPI)
- Known vulnerabilities: none known

## Tags

quantum chemistry simulation, fermionic hamiltonian, quantum algorithm compiler, electronic structure quantum, qubit hamiltonian tools, quantum-computing, chemistry-simulation, hamiltonian-algebra

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