Piquasso

Added

- Python 3.11 support.
- Purification of Gaussian states.
- `PureFockState.get_tensor_representation` for embeddng the state vector into
a tensor with rank equal to the number of modes.
- Batch processing of pure Fock states.
- CVQNN module.
- Support for `tf.function` in `PureFockSimulator`.
- Supporting JAX in `PureFockSimulator`.

Fixed

- Error in custom gradient of passive linear gates in `PureFockSimulator`.

Breaking changes

- Python 3.7 support dropped.
- `TensorflowPureFockSimulator` has been deleted. Instead, one can use
`PureFockSimulator` with `TensorflowCalculator` specified.
- Printing format of Fock states have been changed.
- Renamed `_state_vector` to `state_vector`.

Added

- `dtype` configuration variable in `Config` to set precision of calculations.
- `Kerr` gate calculation in `PureFockSimulator` performance improved.
- Gradient calculation in `TensorflowPureFockSimulator` got improved.
- A method called `PureFockState.mean_position` which calculates the average position
in a specified mode.
- `normalize` configuration variable in `Config` to enable/disable normalization of
states `PureFockSimulator` and `FockSimulator`.

Changed

- `Displacement` parametrization is simplified.
- The autoscaling of single mode gates got deleted.

Fixed

- Vacuum state typing issue fixed in `PureFockSimulator`.
- Calculation error during gradient calculation.

Changed

- Several major performance improvements got implemented in
`TensorflowPureFockSimulator`.

Fixed

- `quantum-blackbird` version got bumped for `numpy` compatibility.
- `Kerr` gate was applied with a wrong equation, it got corrected.
- Typing error was fixed when applying `Interferometer` in
`TensorflowPureFockSimulator`.

Added

- Performance increase for the `PureFockSimulator` and `TensorflowPureFockSimulator`.

Fixed

- `GaussianState.fidelity` gave incorrect results for multiple modes and it
needed to be corrected.
- During Williamson decomposition, sometimes `scipy.linalg.sqrtm` returned with
complex matrices instead of real ones which caused problems so it is manually
casted to real.
- In `TensorflowPureFockSimulator`, the gradient of the displacement gate
matrix was not applied properly to the upstream gradient, a conjugation is
added.
- Using `TensorflowPureFockSimulator`, the input of the `Interferometer` gate
was not converted to a `tensorflow.Tensor` automatically, which has been
included.

Added

- A simulator class called `TensorflowPureFockSimulator`, which uses Tensorflow
and is able to calculate gradients.

Changed

- By enabling Tensorflow support, we dropped support for customizing the
permanent, hafnian and loop hafnian calculations through `Config`.

Fixed

- `SamplingSimulator` along with `Loss` using uniform transmissivity
(transmittance) parameters and `ParticleNumberMeasurement` produced only-zero
samples instead of the expected samples.