Short import for TrotterQRTE

qiskit_algorithms/__init__.py

@@ -30,8 +30,8 @@
 These elements are frequently used in a variety of applications, such as variational optimization,
 time evolution and quantum machine learning.
 
-The quantum algorithms here all use 
-`Primitives <https://qiskit.org/documentation/apidoc/primitives.html>`__ 
+The quantum algorithms here all use
+`Primitives <https://qiskit.org/documentation/apidoc/primitives.html>`__
 to execute quantum circuits. This can be an
 ``Estimator``, which computes expectation values, or a ``Sampler`` which computes
 probability distributions. Refer to the specific algorithm for more information in this regard.
@@ -44,7 +44,7 @@
 The algorithms now presented are grouped by logical function, such
 as minimum eigensolvers, amplitude amplifiers, time evolvers etc. Within each group, the
 algorithms conform to an interface that allows them to be used interchangeably
-by different applications. E.g. a Qiskit Nature application may take a minimum 
+by different applications. E.g. a Qiskit Nature application may take a minimum
 eigensolver to solve a ground state problem, and require it to
 conform to the :class:`.MinimumEigensolver` interface. Any algorithm that conforms to
 the interface, for example :class:`.VQE`, can be used by this application.
@@ -200,6 +200,7 @@
    PVQDResult
    SciPyImaginaryEvolver
    SciPyRealEvolver
+   TrotterQRTE
    VarQITE
    VarQRTE
 
@@ -214,17 +215,6 @@
    time_evolvers.variational
 
 
-Trotterization-based Quantum Real Time Evolution
-++++++++++++++++++++++++++++++++++++++++++++++++
-Trotterization-based quantum time evolution algorithms -
-:class:`~.time_evolvers.trotterization.TrotterQRTE`.
-
-.. autosummary::
-   :toctree:
-
-   time_evolvers.trotterization
-
-
 Miscellaneous
 =============
 Various classes used by qiskit-algorithms that are part of and exposed
@@ -296,6 +286,7 @@
     PVQDResult,
     SciPyImaginaryEvolver,
     SciPyRealEvolver,
+    TrotterQRTE,
     VarQITE,
     VarQRTE,
     VarQTE,
@@ -363,6 +354,7 @@
     "PVQDResult",
     "SciPyRealEvolver",
     "SciPyImaginaryEvolver",
+    "TrotterQRTE",
     "IterativePhaseEstimation",
     "AlgorithmError",
     "estimate_observables",

qiskit_algorithms/time_evolvers/trotterization/__init__.py

@@ -9,25 +9,8 @@
 # Any modifications or derivative works of this code must retain this
 # copyright notice, and modified files need to carry a notice indicating
 # that they have been altered from the originals.
-"""
-Time Evolvers, Trotterization (:mod:`qiskit_algorithms.time_evolvers.variational`)
-==================================================================================
+""" The Time Evolvers, Trotterization package"""
 
-This package contains Trotterization-based Quantum Real Time Evolution algorithm.
-It is compliant with the new Quantum Time Evolution Framework and makes use of
-:class:`qiskit.synthesis.evolution.ProductFormula` and
-:class:`~qiskit.circuit.library.PauliEvolutionGate` implementations.
-
-Trotterization-based Quantum Real Time Evolution
-------------------------------------------------
-
-.. autosummary::
-   :toctree: ../stubs/
-   :nosignatures:
-
-    TrotterQRTE
-"""
-
-from qiskit_algorithms.time_evolvers.trotterization.trotter_qrte import TrotterQRTE
+from .trotter_qrte import TrotterQRTE
 
 __all__ = ["TrotterQRTE"]

qiskit_algorithms/time_evolvers/trotterization/trotter_qrte.py

@@ -30,16 +30,17 @@
 
 class TrotterQRTE(RealTimeEvolver):
     """Quantum Real Time Evolution using Trotterization.
-    Type of Trotterization is defined by a ``ProductFormula`` provided.
+
+    The type of Trotterization is defined by the :class:`~qiskit.synthesis.ProductFormula`
+    provided to the algorithm.
 
     Examples:
 
         .. code-block:: python
 
             from qiskit.quantum_info import Pauli, SparsePauliOp
             from qiskit import QuantumCircuit
-            from qiskit_algorithms import TimeEvolutionProblem
-            from qiskit_algorithms.time_evolvers import TrotterQRTE
+            from qiskit_algorithms import TrotterQRTE, TimeEvolutionProblem
             from qiskit.primitives import Estimator
 
             operator = SparsePauliOp([Pauli("X"), Pauli("Z")])
@@ -60,11 +61,12 @@ def __init__(
     ) -> None:
         """
         Args:
-            product_formula: 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 :attr:`.TimeEvolutionProblem.aux_operators` at every time-step. If ``reps``
-                is larger than 1, the true number of time-steps will be ``num_timesteps * reps``.
+            product_formula: A Lie-Trotter-Suzuki product formula. If ``None`` provided (default),
+                the :class:`~qiskit.synthesis.LieTrotter` 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 :attr:`.TimeEvolutionProblem.aux_operators`
+                at every time-step. If ``reps`` is larger than 1, the true number of time-steps will
+                be ``num_timesteps * reps``.
             num_timesteps: The number of time-steps the full evolution time is divided into
                 (repetitions of ``product_formula``)
             estimator: An estimator primitive used for calculating expectation values of
@@ -85,7 +87,7 @@ def product_formula(self, product_formula: ProductFormula | None):
         """Sets a product formula. If ``None`` provided, sets the Lie-Trotter first order product
         formula with a single repetition."""
         if product_formula is None:
-            product_formula = LieTrotter()
+            product_formula = LieTrotter(reps=1)
         self._product_formula = product_formula
 
     @property

test/time_evolvers/test_trotter_qrte.py

@@ -26,7 +26,7 @@
 from qiskit.primitives import Estimator
 from qiskit.synthesis import SuzukiTrotter, QDrift
 
-from qiskit_algorithms.time_evolvers import TimeEvolutionProblem, TrotterQRTE
+from qiskit_algorithms import TimeEvolutionProblem, TrotterQRTE
 from qiskit_algorithms.utils import algorithm_globals