---
title: SupportsFermionOperator (latest version)
description: API reference for qiskit_fermions.protocols.SupportsFermionOperator in the latest version of qiskit-fermions
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit-fermions/protocols-supports-fermion-operator
---

# SupportsFermionOperator

*class* `SupportsFermionOperator(*args, **kwargs)`

Bases: [`Protocol`](https://docs.python.org/3/library/typing.html#typing.Protocol)

An equivalent of the [`ffsim.SupportsFermionOperator`](https://qiskit-community.github.io/ffsim/api/stubs/ffsim.SupportsFermionOperator.html#ffsim.SupportsFermionOperator "(in ffsim)") protocol.

See [`fermion_operator()`](/docs/api/qiskit-fermions/mappers-library-fermion-operator "qiskit_fermions.mappers.library.fermion_operator") for the type-agnostic helper function dispatching to the method below.

```pycon
>>> from qiskit_fermions.operators import MajoranaOperator
>>> maj_op = MajoranaOperator.from_dict({(0, 1): 1})
>>> fer_op = maj_op._fermion_operator_()
>>> print(format(fer_op.normal_ordered().simplify()))
  0.000000e0 +1.000000e0j * ()
  0.000000e0 -2.000000e0j * (+0 -0)
```

**Protocol Methods**

### \_fermion\_operator\_

`_fermion_operator_()`

Converts this operator into a [`FermionOperator`](/docs/api/qiskit-fermions/operators-fermion-operator "qiskit_fermions.operators.FermionOperator") instance.

**Return type**

[FermionOperator](/docs/api/qiskit-fermions/operators-fermion-operator "qiskit_fermions.operators.FermionOperator")