Lightworks

This release refines the display functionality and documentation, and fixes a couple of issues.

Changelog:
- Added a white background to svg circuit figures to ensure these remain visible in a range of display environments.
- Updated documentation figures to include white background so they are all compatible with the dark mode theme.
- Fixed an issue where introducing detection errors would cause the Sampler random seed to no longer function as expected.
- Fixed an issue where results calculated in the QuickSampler were not properly cached.

PR: 41

Fixes a couple of bugs which could occur in the Sampler, one relating to using an imperfect brightness source and the other to an exception raised if the circuit unitary used by the sampler changes size.

The documentation was also improved, introducing a set of tutorials designed to aide in familiarisation with Lightworks.

PR: 36

Fixed a bug with get_all_params method in circuit and removed some old code from the package.

PR: 33

With the inclusion of qubit components in Lightworks 1.2, it quickly became clear that trying to identify and manage heralding modes/photons was very difficult when adding more than a single gate. This update therefore adds the integration of heralds into the circuit object, enabling heralds to be abstracted and internally managed in a visual and logical way.

Changelog:

- Integrated heralds within the circuit object, including support for creation of functional heralded sub-circuits which can then be added to a larger circuit.
- Updated display methods to support the inclusion of heralds.
- Included support for heralds within all simulation objects, meaning these modes don't need to be specified by users.
- Minor bug fixes with SimulationResult + library restructuring.

PR: 23

This release added a set of standard components for implementing photonic qubit gates and expanded on the documentation.

Changelog:
- Added single and two qubit gate circuits which can be used to quickly implement required qubit processing.
- Improved docs, including sections of backend usage, extra Simulator examples and some information on new qubit components. Also corrected some grammatical issues.
- Removed some redundant functions and fidelity calculation as this was not well defined.
- Added slots to States and AnnotatedStates to reduce memory usage, also removed pre-calculation of mode number.
- Added method in state to perform validation on the values, checking that they are all integers and are not negative.
- Adjusted the indexing method used in SimualtionResult, now values are accessed with [input, output] instead of [input:output].

PR: 15

This release of Lightworks reworks the backend to provide a framework for a future expansion of backend options. A basic SLOS implementation has also been added to the Sampler for initial testing of the backend functionality.

There was also a number of additional updates in this release:
- Improved performance of some components.
- Expanded on unit tests, including using parametrization in pytest to quickly check a range of values.
- Updated docs, detailing the Unitary object and adding a demo notebook for the heralded CNOT.

PR: 8