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---
title: PauliEvolutionGate
description: API reference for qiskit.circuit.library.PauliEvolutionGate
in_page_toc_min_heading_level: 1
python_api_type: class
python_api_name: qiskit.circuit.library.PauliEvolutionGate
---
# PauliEvolutionGate
<Class id="qiskit.circuit.library.PauliEvolutionGate" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.24/qiskit/circuit/library/pauli_evolution.py" signature="PauliEvolutionGate(operator, time=1.0, label=None, synthesis=None)" modifiers="class">
Bases: [`Gate`](qiskit.circuit.Gate "qiskit.circuit.gate.Gate")
Time-evolution of an operator consisting of Paulis.
For an operator $H$ consisting of Pauli terms and (real) evolution time $t$ this gate implements
$$
U(t) = e^{-itH}.
$$
This gate serves as a high-level definition of the evolution and can be synthesized into a circuit using different algorithms.
The evolution gates are related to the Pauli rotation gates by a factor of 2. For example the time evolution of the Pauli $X$ operator is connected to the Pauli $X$ rotation $R_X$ by
$$
U(t) = e^{-itX} = R_X(2t).
$$
**Examples:**
```python
from qiskit.circuit import QuantumCircuit
from qiskit.circuit.library import PauliEvolutionGate
from qiskit.opflow import I, Z, X
# build the evolution gate
operator = (Z ^ Z) - 0.1 * (X ^ I)
evo = PauliEvolutionGate(operator, time=0.2)
# plug it into a circuit
circuit = QuantumCircuit(2)
circuit.append(evo, range(2))
print(circuit.draw())
```
The above will print (note that the `-0.1` coefficient is not printed!):
```python
┌──────────────────────────┐
q_0: ┤0 ├
│ exp(-it (ZZ + XI))(0.2) │
q_1: ┤1 ├
└──────────────────────────┘
```
**References:**
\[1] G. Li et al. Paulihedral: A Generalized Block-Wise Compiler Optimization Framework For Quantum Simulation Kernels (2021). \[[arXiv:2109.03371](https://arxiv.org/abs/2109.03371)]
**Parameters**
* **operator** ([*Pauli*](qiskit.quantum_info.Pauli "qiskit.quantum_info.Pauli") *|*[*PauliOp*](qiskit.opflow.primitive_ops.PauliOp "qiskit.opflow.primitive_ops.PauliOp") *|*[*SparsePauliOp*](qiskit.quantum_info.SparsePauliOp "qiskit.quantum_info.SparsePauliOp") *|*[*PauliSumOp*](qiskit.opflow.primitive_ops.PauliSumOp "qiskit.opflow.primitive_ops.PauliSumOp") *| list*) The operator to evolve. Can also be provided as list of non-commuting operators where the elements are sums of commuting operators. For example: `[XY + YX, ZZ + ZI + IZ, YY]`.
* **time** (*Union\[int, float,* [*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.ParameterExpression")*]*) The evolution time.
* **label** (*Optional\[str]*) A label for the gate to display in visualizations. Per default, the label is set to `exp(-it <operators>)` where `<operators>` is the sum of the Paulis. Note that the label does not include any coefficients of the Paulis. See the class docstring for an example.
* **synthesis** (*Optional\[*[*EvolutionSynthesis*](qiskit.synthesis.EvolutionSynthesis "qiskit.synthesis.EvolutionSynthesis")*]*) A synthesis strategy. If None, the default synthesis is the Lie-Trotter product formula with a single repetition.
## Methods Defined Here
<span id="qiskit-circuit-library-paulievolutiongate-validate-parameter" />
### validate\_parameter
<Function id="qiskit.circuit.library.PauliEvolutionGate.validate_parameter" signature="PauliEvolutionGate.validate_parameter(parameter)">
Gate parameters should be int, float, or ParameterExpression
**Return type**
float | [*ParameterExpression*](qiskit.circuit.ParameterExpression "qiskit.circuit.parameterexpression.ParameterExpression")
</Function>
## Attributes
### condition\_bits
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.condition_bits">
Get Clbits in condition.
</Attribute>
### decompositions
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.decompositions">
Get the decompositions of the instruction from the SessionEquivalenceLibrary.
</Attribute>
### definition
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.definition">
Return definition in terms of other basic gates.
</Attribute>
### duration
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.duration">
Get the duration.
</Attribute>
### label
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.label">
Return instruction label
</Attribute>
### name
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.name">
Return the name.
</Attribute>
### num\_clbits
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.num_clbits">
Return the number of clbits.
</Attribute>
### num\_qubits
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.num_qubits">
Return the number of qubits.
</Attribute>
### params
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.params">
return instruction params.
</Attribute>
### time
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.time">
Return the evolution time as stored in the gate parameters.
**Returns**
The evolution time.
</Attribute>
### unit
<Attribute id="qiskit.circuit.library.PauliEvolutionGate.unit">
Get the time unit of duration.
</Attribute>
</Class>