104 lines
5.5 KiB
Plaintext
104 lines
5.5 KiB
Plaintext
---
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title: TrotterQRTE
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description: API reference for qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE
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in_page_toc_min_heading_level: 1
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python_api_type: class
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python_api_name: qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE
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---
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# TrotterQRTE
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<Class id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE" isDedicatedPage={true} github="https://github.com/qiskit/qiskit/tree/stable/0.45/qiskit/algorithms/time_evolvers/trotterization/trotter_qrte.py" signature="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE(product_formula=None, estimator=None, num_timesteps=1)" modifiers="class">
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Bases: [`RealTimeEvolver`](qiskit.algorithms.RealTimeEvolver "qiskit.algorithms.time_evolvers.real_time_evolver.RealTimeEvolver")
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Quantum Real Time Evolution using Trotterization. Type of Trotterization is defined by a `ProductFormula` provided.
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**Examples**
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```python
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from qiskit.opflow import PauliSumOp
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from qiskit.quantum_info import Pauli, SparsePauliOp
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from qiskit import QuantumCircuit
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from qiskit.algorithms import TimeEvolutionProblem
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from qiskit.algorithms.time_evolvers import TrotterQRTE
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from qiskit.primitives import Estimator
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operator = PauliSumOp(SparsePauliOp([Pauli("X"), Pauli("Z")]))
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initial_state = QuantumCircuit(1)
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time = 1
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evolution_problem = TimeEvolutionProblem(operator, time, initial_state)
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# LieTrotter with 1 rep
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estimator = Estimator()
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trotter_qrte = TrotterQRTE(estimator=estimator)
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evolved_state = trotter_qrte.evolve(evolution_problem).evolved_state
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```
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**Parameters**
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* **product\_formula** ([*ProductFormula*](qiskit.synthesis.ProductFormula "qiskit.synthesis.ProductFormula") *| None*) – A Lie-Trotter-Suzuki product formula. If `None` provided, the Lie-Trotter first order product formula with a single repetition is used. `reps` should be 1 to obtain a number of time-steps equal to `num_timesteps` and an evaluation of [`TimeEvolutionProblem.aux_operators`](qiskit.algorithms.TimeEvolutionProblem#aux_operators "qiskit.algorithms.TimeEvolutionProblem.aux_operators") at every time-step. If `reps` is larger than 1, the true number of time-steps will be `num_timesteps * reps`.
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* **num\_timesteps** ([*int*](https://docs.python.org/3/library/functions.html#int "(in Python v3.12)")) – The number of time-steps the full evolution time is devided into (repetitions of `product_formula`)
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* **estimator** ([*BaseEstimator*](qiskit.primitives.BaseEstimator "qiskit.primitives.BaseEstimator") *| None*) – An estimator primitive used for calculating expectation values of `TimeEvolutionProblem.aux_operators`.
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## Attributes
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### estimator
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<Attribute id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE.estimator">
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Returns an estimator.
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</Attribute>
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### num\_timesteps
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<Attribute id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE.num_timesteps">
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Returns the number of timesteps.
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</Attribute>
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### product\_formula
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<Attribute id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE.product_formula">
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Returns a product formula.
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</Attribute>
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## Methods
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### evolve
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<Function id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE.evolve" signature="evolve(evolution_problem)">
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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 the `init_state` and on the evolved state at every step (`num_timesteps` times) using an estimator primitive provided.
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**Parameters**
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**evolution\_problem** ([*TimeEvolutionProblem*](qiskit.algorithms.TimeEvolutionProblem "qiskit.algorithms.time_evolvers.time_evolution_problem.TimeEvolutionProblem")) – Instance defining evolution problem. For the included Hamiltonian, `Pauli` or `PauliSumOp` are supported by TrotterQRTE.
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**Returns**
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Evolution result that includes an evolved state as a quantum circuit and, optionally, auxiliary operators evaluated for a resulting state on an estimator primitive.
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**Raises**
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* [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.12)") – If `t_param` is not set to `None` in the `TimeEvolutionProblem` (feature not currently supported).
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* [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.12)") – If `aux_operators` provided in the time evolution problem but no estimator provided to the algorithm.
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* [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.12)") – If the `initial_state` is not provided in the `TimeEvolutionProblem`.
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* [**ValueError**](https://docs.python.org/3/library/exceptions.html#ValueError "(in Python v3.12)") – If an unsupported Hamiltonian type is provided.
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**Return type**
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[*TimeEvolutionResult*](qiskit.algorithms.TimeEvolutionResult "qiskit.algorithms.time_evolvers.time_evolution_result.TimeEvolutionResult")
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</Function>
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### supports\_aux\_operators
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<Function id="qiskit.algorithms.time_evolvers.trotterization.TrotterQRTE.supports_aux_operators" signature="supports_aux_operators()" modifiers="classmethod">
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Whether computing the expectation value of auxiliary operators is supported.
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**Returns**
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`True` if `aux_operators` expectations in the `TimeEvolutionProblem` can be evaluated, `False` otherwise.
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**Return type**
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[bool](https://docs.python.org/3/library/functions.html#bool "(in Python v3.12)")
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</Function>
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</Class>
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