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

# ImaginaryEvolver

*class* `qiskit.algorithms.ImaginaryEvolver`

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

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

Deprecated: Interface for Quantum Imaginary Time Evolution.

The ImaginaryEvolver interface has been superseded by the `qiskit.algorithms.time_evolvers.ImaginaryTimeEvolver` interface. This interface will be deprecated in a future release and subsequently removed after that.

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

## Methods

### evolve

*abstract* `evolve(evolution_problem)`

Perform imaginary time evolution $\exp(-\tau H)|\Psi\rangle$.

Evolves an initial state $|\Psi\rangle$ for an imaginary time $\tau$ under a Hamiltonian $H$, as provided in the `evolution_problem`.

**Parameters**

**evolution\_problem** ([*EvolutionProblem*](/docs/api/qiskit/0.46/qiskit.algorithms.EvolutionProblem "qiskit.algorithms.evolvers.evolution_problem.EvolutionProblem")) – The definition of the evolution problem.

**Returns**

Evolution result which includes an evolved quantum state.

**Return type**

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