ClassicalFunction compiler
qiskit.circuit.classicalfunction
Overview
The classical function compiler provides the necessary tools to map a classical potentially irreversible functions into quantum circuits. Below is a simple example of how to synthesize a simple boolean function defined using Python into a QuantumCircuit:
from qiskit.circuit.classicalfunction import classical_function from qiskit.circuit.classicalfunction.types import Int1 @classical_function def grover_oracle(a: Int1, b: Int1, c: Int1, d: Int1) -> Int1: return (not a and b and not c and d) quantum_circuit = grover_oracle.synth(registerless=False) quantum_circuit.draw('text')
a: ──o── │ b: ──■── │ c: ──o── │ d: ──■── ┌─┴─┐ return: ┤ X ├ └───┘
Following Qiskit’s little-endian bit ordering convention, the left-most bit (a
) is the most significant bit and the right-most bit (d
) is the least significant bit.
The functionality of qiskit.circuit.classicalfunction requires tweedledum, which isn’t available on all platforms (up to Python version 3.11). See tweedledum installation guide for more details.
Supplementary Information
Tweedledum
Tweedledum is a C++-17 header-only library that implements a large set of reversible (and quantum) synthesis, optimization, and mapping algorithms. The classical function compiler relies on it and its dependencies to both represent logic networks and synthesize them into quantum circuits.
ClassicalFunction data types
At the moment, the only type supported by the classical_function compilers is qiskit.circuit.classicalfunction.types.Int1
. The classical function function to parse must include type hints (just Int1
for now). The resulting gate will be a gate in the size of the sum of all the parameters and the return.
The type Int1
means the classical function will only operate at bit level.
ClassicalFunction compiler API
classical_function
Decorator for a classical function that returns a ClassicalFunction object.
classical_function
qiskit.circuit.classicalfunction.classical_function(func)
Parses and type checks the callable func
to compile it into an ClassicalFunction
that can be synthesized into a QuantumCircuit
.
Parameters
func (callable) – A callable (with type hints) to compile into an ClassicalFunction
.
Returns
An object that can synthesis into a QuantumCircuit (via synth()
method).
Return type
ClassicalFunction
ClassicalFunction (source[, name]) | Represent a classical function and its logic network. |
BooleanExpression (expression[, name, var_order]) | The Boolean Expression gate. |
Exceptions
ClassicalFunctionCompilerTypeError (*message) | ClassicalFunction compiler type error. |
ClassicalFunctionParseError (*message) | ClassicalFunction compiler parse error. |
ClassicalFunctionCompilerTypeError (*message) | ClassicalFunction compiler type error. |