Utilities

Module name: blackbird.utils

This module contains utility functions for Blackbird programs, including generating directed acyclic graphs, and pattern matching and Blackbird programs and templates.

Summary

TemplateError Exception class for template related errors
to_DiGraph(program) Convert a Blackbird program to a directed acyclic graph.
match_template(template, program) Match a template against a Blackbird program, returning template parameter values.

Code details

class Command(name, args, kwargs, modes)

namedtuple: encapsulate a specific quantum operation

args

Alias for field number 1

kwargs

Alias for field number 2

modes

Alias for field number 3

name

Alias for field number 0

exception TemplateError[source]

Exception class for template related errors

to_DiGraph(program)[source]

Convert a Blackbird program to a directed acyclic graph.

The resulting graph has nodes representing quantum operations, and edges representing dependent/successor operations.

Each node is labelled by an integer; note attributes are used to store information about the node:

  • 'name' (str): name of the quantum operation (e.g., 'S2gate')
  • 'args' (list): positional arguments of the operation
  • 'kwargs' (dict): keyword arguments of the operation
  • 'modes' (tuple[int]): modes the operation acts on
Parameters:program (blackbird.Program) – a Blackbird program
Returns:the directed acyclic graph representing the quantum program
Return type:networkx.DiGraph
match_template(template, program)[source]

Match a template against a Blackbird program, returning template parameter values.

For example, consider the following template and program:

template = blackbird.loads("""\
name prog
version 1.0

Dgate(-{r}, 0.45) | 1
Vac | 2
Sgate({r}, 2*{phi}-1) | 0
""")

program = blackbird.loads("""\
name prog
version 1.0

Sgate(0.543, -1.432*pi) | 0
Dgate(-0.543, 0.45) | 1
Vac | 2
""")

By applying the match_template function, we can match the template parameters:

>>> res = match_template(template, program)
>>> print(res)
{'r': 0.543, 'phi': -1.74938033997029}

Verifying this is correct:

>>> print((-1.432*np.pi+1)/2)
-1.7493803399702919

Note

The template and the Blackbird program to match must have the same version number and target, otherwise an TemplateError will be raised.

Parameters:
  • template (blackbird.Program) – the Blackbird template
  • program (blackbird.Program) – a Blackbird program to match against the template
Returns:

mapping from the template parameter name to a numerical value.

Return type:

dict[str, Number]