---
title: Approximate quantum compilation (AQC-Tensor) release notes
description: Changes made to Approximate quantum compilation (AQC-Tensor)
source: https://quantum.cloud.ibm.com/docs/en/api/qiskit-addon-aqc-tensor/release-notes
---

# Approximate quantum compilation (AQC-Tensor) release notes

## 0.3.1

### Bug Fixes

- Fixed the quimb backend to be compatible with versions of quimb following the [CircuitBase refactor](https://github.com/jcmgray/quimb/pull/399). quimb 1.14.0 is the last released version before the refactor.

## 0.3.0

### New Features

- Support for Python 3.14.

- The quimb backend now supports evaluating the gradient of multi-parameter gates, as long as the Qiskit gate maps directly to a quimb gate without change of parameters. Currently, [`XXPlusYYGate`](/docs/api/qiskit/qiskit.circuit.library.XXPlusYYGate) is the only multi-parameter gate supported by qiskit-quimb.

### Upgrade Notes

- The quimb backend now requires the following minimum versions: quimb 0.11.0 and qiskit-quimb 0.0.9.

### Bug Fixes

- This adds a workaround for an issue sometimes encountered when calling [`TwoQubitWeylDecomposition`](/docs/api/qiskit/qiskit.synthesis.TwoQubitWeylDecomposition) inside [`generate_ansatz_from_circuit()`](/docs/api/qiskit-addon-aqc-tensor/ansatz-generation#qiskit_addon_aqc_tensor.ansatz_generation.generate_ansatz_from_circuit "qiskit_addon_aqc_tensor.ansatz_generation.generate_ansatz_from_circuit"). Sometimes an error is thrown despite the input matrix being unitary to numerical precision, and returning ``is_unitary()`()`` as `True`. This is an ongoing issue in qiskit, see [https://github.com/Qiskit/qiskit/issues/4159](https://github.com/Qiskit/qiskit/issues/4159) for more details.

  With this workaround, any time the error is encountered, it will retry by transpiling the two-qubit circuit (from which the matrix is derived) prior to passing the matrix to [`TwoQubitWeylDecomposition`](/docs/api/qiskit/qiskit.synthesis.TwoQubitWeylDecomposition). It should be noted that this is does not fix the root issue, and is not guaranteed to always work, but has been observed to work for some instances.

## 0.2.0

### Prelude

This release renames the primary objective to [`MaximizeStateFidelity`](/docs/api/qiskit-addon-aqc-tensor/objective#qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity "qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity") and adds support for Qiskit 2.0.

### New Features

- Adds the [`parametrize_circuit()`](/docs/api/qiskit-addon-aqc-tensor/ansatz-generation#qiskit_addon_aqc_tensor.ansatz_generation.parametrize_circuit "qiskit_addon_aqc_tensor.ansatz_generation.parametrize_circuit") function for generating a parametrized version of a given circuit. In contrast to [`generate_ansatz_from_circuit()`](/docs/api/qiskit-addon-aqc-tensor/ansatz-generation#qiskit_addon_aqc_tensor.ansatz_generation.generate_ansatz_from_circuit "qiskit_addon_aqc_tensor.ansatz_generation.generate_ansatz_from_circuit"), `parametrize_circuit` does not change the types of gates in the circuit. It simply replaces numerical parameters with free parameters.

- Support for Python 3.13.

### Upgrade Notes

- The `OneMinusFidelity` objective function has been renamed and is now known as [`MaximizeStateFidelity`](/docs/api/qiskit-addon-aqc-tensor/objective#qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity "qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity"). As a related change, one should now call the [`loss_function()`](/docs/api/qiskit-addon-aqc-tensor/objective#qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity.loss_function "qiskit_addon_aqc_tensor.objective.MaximizeStateFidelity.loss_function") method to obtain the value and gradient of the loss function, instead of calling the instance directly (through its `__call__` method).

- Qiskit SDK version 1.3 or higher is now required. Qiskit SDK version 2.0 is now supported.

### Bug Fixes

- This release fixes the import of `quimb_gate()` to work on versions of qiskit-quimb greater than 0.0.5. The aforementioned function is now imported from the toplevel `qiskit_quimb` instead of `qiskit_quimb.circuit`.

## 0.1.1

### New Features

- This release adds quimb-autograd as an optional dependency, so that one can now run `pip install 'qiskit-addon-aqc-tensor[quimb-autograd]'` to install the addon along with quimb and autograd.

## 0.1.0

### Prelude

Initial release.