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:orphan:

Release 0.41.0-dev (development release)

New features since last release

Improvements 🛠

  • The higher order primitives in program capture can now accept inputs with abstract shapes. (#6786)

  • The PlxprInterpreter classes can now handle creating dynamic arrays via jnp.ones, jnp.zeros, jnp.arange, and jnp.full. #6865)

  • QNode objects now have an update method that allows for re-configuring settings like diff_method, mcm_method, and more. This allows for easier on-the-fly adjustments to workflows. Any arguments not specified will retain their original value. (#6803)

    After constructing a QNode,

    import pennylane as qml

@qml.qnode(device=qml.device("default.qubit"))
def circuit():
  qml.H(0)
  qml.CNOT([0,1])
  return qml.probs()

    its settings can be modified with update, which returns a new QNode object. Here is an example of updating a QNode's diff_method:

    >>> print(circuit.diff_method)
best
>>> new_circuit = circuit.update(diff_method="parameter-shift")
>>> print(new_circuit.diff_method)
'parameter-shift'

  • Devices can now configure whether or not ML framework data is sent to them via an ExecutionConfig.convert_to_numpy parameter. This is not used on default.qubit due to compilation overheads when jitting. (#6788) (#6869)

  • The coefficients of observables now have improved differentiability. (#6598)

  • An empty basis set in qml.compile is now recognized as valid, resulting in decomposition of all operators that can be decomposed. (#6821)

  • An informative error is raised when a QNode with diff_method=None is differentiated. (#6770)

  • qml.gradients.finite_diff_jvp has been added to compute the jvp of an arbitrary numeric function. (#6853)

  • With program capture enabled, QNode's can now be differentiated with diff_method="finite-diff". (#6853)

  • The requested diff_method is now validated when program capture is enabled. (#6852)

Breaking changes 💔

  • MultiControlledX no longer accepts strings as control values. (#6835)

  • The input argument control_wires of MultiControlledX has been removed. (#6832) (#6862)

  • qml.execute now has a collection of keyword-only arguments. (#6598)

  • The decomp_depth argument in :func:~pennylane.transforms.set_decomposition has been removed. (#6824)

  • The max_expansion argument in :func:~pennylane.devices.preprocess.decompose has been removed. (#6824)

  • The tape and qtape properties of QNode have been removed. Instead, use the qml.workflow.construct_tape function. (#6825)

  • The gradient_fn keyword argument to qml.execute has been removed. Instead, it has been replaced with diff_method. (#6830)

  • The QNode.get_best_method and QNode.best_method_str methods have been removed. Instead, use the qml.workflow.get_best_diff_method function. (#6823)

  • The output_dim property of qml.tape.QuantumScript has been removed. Instead, use method shape of QuantumScript or MeasurementProcess to get the same information. (#6829)

  • Removed method qsvt_legacy along with its private helper _qsp_to_qsvt (#6827)

Deprecations 👋

  • The mcm_method keyword in qml.execute has been deprecated. Instead, use the mcm_method and postselect_mode arguments. (#6807)

  • Specifying gradient keyword arguments as any additional keyword argument to the qnode is deprecated and will be removed in v0.42. The gradient keyword arguments should be passed to the new keyword argument gradient_kwargs via an explicit dictionary. This change will improve qnode argument validation. (#6828)

  • The qml.gradients.hamiltonian_grad function has been deprecated. This gradient recipe is not required with the new operator arithmetic system. (#6849)

  • The inner_transform_program and config keyword arguments in qml.execute have been deprecated. If more detailed control over the execution is required, use qml.workflow.run with these arguments instead. (#6822) (#6879)

Internal changes ⚙️

  • The source code has been updated use black 25.1.0 (#6897)

  • Improved the InterfaceEnum object to prevent direct comparisons to str objects. (#6877)

  • Added a QmlPrimitive class that inherits jax.core.Primitive to a new qml.capture.custom_primitives module. This class contains a prim_type property so that we can differentiate between different sets of PennyLane primitives. Consequently, QmlPrimitive is now used to define all PennyLane primitives. (#6847)

  • The RiemannianGradientOptimizer has been updated to take advantage of newer features. (#6882)

Documentation 📝

  • The docstrings for qml.unary_mapping, qml.binary_mapping, qml.christiansen_mapping, qml.qchem.localize_normal_modes, and qml.qchem.VibrationalPES have been updated to include better code examples. (#6717)

  • The docstrings for qml.qchem.localize_normal_modes and qml.qchem.VibrationalPES have been updated to include examples that can be copied. (#6834)

  • Fixed a typo in the code example for qml.labs.dla.lie_closure_dense. (#6858)

Bug fixes 🐛

  • The interface is now detected from the data in the circuit, not the arguments to the QNode. This allows interface data to be strictly passed as closure variables and still be detected. (#6892)

  • BasisState now casts its input to integers. (#6844)

Contributors ✍️

This release contains contributions from (in alphabetical order):

Yushao Chen, Isaac De Vlugt, Diksha Dhawan, Pietropaolo Frisoni, Marcus Gisslén, Christina Lee, Mudit Pandey, Andrija Paurevic