# PauliTrotterEvolution

`qiskit.opflow.evolutions.PauliTrotterEvolution(trotter_mode='trotter', reps=1)`

Bases: `EvolutionBase`

Deprecated: An Evolution algorithm replacing exponentiated sums of Paulis by changing them each to the Z basis, rotating with an rZ, changing back, and Trotterizing.

More specifically, we compute basis change circuits for each Pauli into a single-qubit Z, evolve the Z by the desired evolution time with an rZ gate, and change the basis back using the adjoint of the original basis change circuit. For sums of Paulis, the individual Pauli evolution circuits are composed together by Trotterization scheme.

The class `qiskit.opflow.evolutions.pauli_trotter_evolution.PauliTrotterEvolution`

is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. For code migration guidelines, visit https://qisk.it/opflow_migration (opens in a new tab).

**Parameters**

**trotter_mode**(*str*(opens in a new tab)*|**TrotterizationBase**| None*) – A string (‘trotter’, ‘suzuki’, or ‘qdrift’) to pass to the TrotterizationFactory, or a TrotterizationBase, indicating how to combine individual Pauli evolution circuits to equal the exponentiation of the Pauli sum.**reps**(*int*(opens in a new tab)*| None*) – How many Trotterization repetitions to make, to improve the approximation accuracy.**evolution.**(*# TODO uncomment when we implement Abelian grouped*) –**group_paulis**(*#*) – Whether to group Pauli sums into Abelian**sub-groups**(*#*) –**group**(*so a single diagonalization circuit can be used for each*) –**Pauli.**(*# rather than each*) –

## Attributes

### trotter

TrotterizationBase used to evolve SummedOps.

## Methods

### convert

`convert(operator)`

Traverse the operator, replacing `EvolvedOps`

with `CircuitOps`

containing Trotterized evolutions equalling the exponentiation of -i * operator.

**Parameters**

**operator** (*OperatorBase*) – The Operator to convert.

**Returns**

The converted operator.

**Return type**

### evolution_for_abelian_paulisum

`evolution_for_abelian_paulisum(op_sum)`

Evolution for abelian pauli sum

**Return type**

### evolution_for_pauli

`evolution_for_pauli(pauli_op)`

Compute evolution Operator for a single Pauli using a `PauliBasisChange`

.

**Parameters**

**pauli_op** (*PauliOp*) – The `PauliOp`

to evolve.

**Returns**

A `PrimitiveOp`

, either the evolution `CircuitOp`

or a `PauliOp`

equal to the identity if pauli_op is the identity.

**Return type**