Release 0.3.2

[0.3.2] - 2025-08-12

Added

• #320: Method for Pattern: compose

• #310: Method for OpenGraph: compose

• #277: Methods for pretty-printing Pattern: to_ascii,
  to_unicode, to_latex.

• #300: Branch selection in simulation: in addition to
  RandomBranchSelector which corresponds to the strategy that was
  already implemented, the user can use FixedBranchSelector,
  ConstBranchSelector, or define a custom branch selection by
  deriving the abstract class BranchSelector.

• #312: The separation between TensorNetworkBackend and backends
  that operate on a full-state representation, such as
  StatevecBackend and DensityMatrixBackend, is now clearer with
  the introduction of the abstract classes DenseStateBackend and
  DenseState, which derive from Backend and BackendState,
  respectively. StatevecBackend and DensityMatrixBackend inherit
  from DenseStateBackend, while Statevec and DensityMatrix
  inherit from DenseState. Note that the class hierarchy of
  BackendState mirrors that of Backend.

• #322: Added a new optimization module containing:

  • a functional version of standardize that returns a standardized
    pattern as a new object;

  • a function incorporate_pauli_results that returns an equivalent
    pattern in which the results are incorporated into measurement
    and correction domains.
    The resulting pattern is suitable for flow analysis. In
    particular, if a pattern has a flow, it is preserved by
    perform_pauli_measurements after applying standardize and
    incorporate_pauli_results.

Fixed

• #314, #322: The method Pattern.standardize() now correctly returns
  an equivalent pattern even in the presence of C commands, or raises
  an error if no standardized form exists.

• #277: The result of repr() for Pattern, Circuit, Command,
  Instruction, Plane, Axis and Sign is now a valid Python
  expression and is more readable.

• #235, #252, #273: The open graph representation is now compatible
  with pyzx 0.9, and conventions have been fixed to ensure that the
  semantics is preserved between circuits, ZX graphs, open graphs and
  patterns.

• #302, #308, #312: Pattern, Circuit, PatternSimulator, and
  backends are now type-checked.

Changed

• #277: The method Pattern.print_pattern is now deprecated.

• #300: pr_calc parameter is removed in back-end initializers.
  The user can specify pr_calc in the constructor of
  RandomBranchSelector instead.

• #300: rng is no longer stored in the backends; it is now passed as
  an optional argument to each simulation method.

• #261: Moved all device interface functionalities to an external
  library and removed their implementation from this library.

• #314, #322: The method Pattern.standardize() now places C commands
  after X and Z commands, making the resulting patterns suitable for
  flow analysis.
  The flow_from_pattern functions now fail if the input pattern is
  not strictly standardized (as checked by
  Pattern.is_standard(strict=True), which requires C commands to be
  last).
  Note: the method perform_pauli_measurements still places C
  commands before X and Z commands.

• #312: Backend's State has been renamed to BackendState to avoid
  a name conflict with the State class defined in graphix.states,
  which represents the state of a single qubit.

• #312: Backend[StateT_co] and DenseStateBackend[DenseStateT_co]
  are now parameterized by covariant type variables, allowing
  subclasses to narrow the type of the state field to match their
  specific state representation. Covariance is sound in this context
  because the classes are frozen, and it ensures that
  Backend[BackendState] is a supertype of all backend classes.