---
title: TrotterQRTE (v0.46)
description: API reference for qiskit.algorithms.TrotterQRTE in qiskit v0.46
source: https://eu-de.quantum.cloud.ibm.com/docs/en/api/qiskit/0.46/qiskit.algorithms.TrotterQRTE
---

# TrotterQRTE

*class* `qiskit.algorithms.TrotterQRTE(product_formula=None, expectation=None, quantum_instance=None)`

[GitHub](https://github.com/qiskit/qiskit/tree/stable/0.46/qiskit/algorithms/evolvers/trotterization/trotter_qrte.py)

Bases: [`RealEvolver`](/docs/api/qiskit/0.46/qiskit.algorithms.RealEvolver "qiskit.algorithms.evolvers.real_evolver.RealEvolver")

Deprecated: Quantum Real Time Evolution using Trotterization.

The TrotterQRTE class has been superseded by the [`qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE`](/docs/api/qiskit/0.46/qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE "qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE") class. This class will be deprecated in a future release and subsequently removed after that.

Type of Trotterization is defined by a ProductFormula provided.

Examples:

```python
from qiskit.opflow import X, Z, Zero
from qiskit.algorithms import EvolutionProblem, TrotterQRTE
from qiskit import BasicAer
from qiskit.utils import QuantumInstance

operator = X + Z
initial_state = Zero
time = 1
evolution_problem = EvolutionProblem(operator, 1, initial_state)
# LieTrotter with 1 rep
backend = BasicAer.get_backend("statevector_simulator")
quantum_instance = QuantumInstance(backend=backend)
trotter_qrte = TrotterQRTE(quantum_instance=quantum_instance)
evolved_state = trotter_qrte.evolve(evolution_problem).evolved_state
```

> **Deprecated since version 0.24.0**
>
> The class `qiskit.algorithms.evolvers.trotterization.trotter_qrte.TrotterQRTE` is deprecated as of qiskit-terra 0.24.0. It will be removed no earlier than 3 months after the release date. Instead, use the class `qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE`. See [https://qisk.it/algo\_migration](https://qisk.it/algo_migration) for a migration guide.

**Parameters**

- **product\_formula** ([*ProductFormula*](/docs/api/qiskit/0.46/qiskit.synthesis.ProductFormula "qiskit.synthesis.ProductFormula") *| None*) – A Lie-Trotter-Suzuki product formula. The default is the Lie-Trotter first order product formula with a single repetition.
- **expectation** ([*ExpectationBase*](/docs/api/qiskit/0.46/qiskit.opflow.expectations.ExpectationBase "qiskit.opflow.expectations.ExpectationBase") *| None*) – An instance of ExpectationBase which defines a method for calculating expectation values of EvolutionProblem.aux\_operators.
- **quantum\_instance** ([*QuantumInstance*](/docs/api/qiskit/0.46/qiskit.utils.QuantumInstance "qiskit.utils.QuantumInstance")  *|*[*Backend*](/docs/api/qiskit/0.46/qiskit.providers.Backend "qiskit.providers.Backend") *| None*) – A quantum instance used for calculating expectation values of EvolutionProblem.aux\_operators.

## Attributes

### expectation

Returns an expectation used in the algorithm.

### product\_formula

Returns a product formula used in the algorithm.

### quantum\_instance

Returns a quantum instance used in the algorithm.

## Methods

### evolve

`evolve(evolution_problem)`

Evolves a quantum state for a given time using the Trotterization method based on a product formula provided. The result is provided in the form of a quantum circuit. If auxiliary operators are included in the `evolution_problem`, they are evaluated on an evolved state using a backend provided.

> **Note**
>
> Time-dependent Hamiltonians are not yet supported.

**Parameters**

**evolution\_problem** ([*EvolutionProblem*](/docs/api/qiskit/0.46/qiskit.algorithms.EvolutionProblem "qiskit.algorithms.evolvers.evolution_problem.EvolutionProblem")) – Instance defining evolution problem. For the included Hamiltonian, `PauliOp`, `SummedOp` or `PauliSumOp` are supported by TrotterQRTE.

**Returns**

Evolution result that includes an evolved state as a quantum circuit and, optionally, auxiliary operators evaluated for a resulting state on a backend.

**Raises**

- [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError) – If `t_param` is not set to None in the EvolutionProblem (feature not currently supported).
- [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError) – If the `initial_state` is not provided in the EvolutionProblem.

**Return type**

[*EvolutionResult*](/docs/api/qiskit/0.46/qiskit.algorithms.EvolutionResult "qiskit.algorithms.evolvers.evolution_result.EvolutionResult")

### supports\_aux\_operators

*classmethod* `supports_aux_operators()`

Whether computing the expectation value of auxiliary operators is supported.

**Returns**

**True if `aux_operators` expectations in the EvolutionProblem can be evaluated, False**

otherwise.

**Return type**

[bool](https://docs.python.org/3/library/functions.html#bool)