IntegerComparator

class qiskit.circuit.library.IntegerComparator(num_state_qubits=None, value=None, geq=True, name='cmp')

Bases: BlueprintCircuit

Integer Comparator.

Operator compares basis states $|i\rangle_n$ against a classically given integer $L$ of fixed value and flips a target qubit if $i \geq L$ (or $<$ depending on the parameter geq):

|i\rangle_n |0\rangle \mapsto |i\rangle_n |i \geq L\rangle

This operation is based on two’s complement implementation of binary subtraction but only uses carry bits and no actual result bits. If the most significant carry bit (the results bit) is 1, the $\geq$ condition is True otherwise it is False.

Create a new fixed value comparator circuit.

Parameters

num_state_qubits (int | None) – Number of state qubits. If this is set it will determine the number of qubits required for the circuit.
value (int | None) – The fixed value to compare with.
geq (bool) – If True, evaluate a >= condition, else <.
name (str) – Name of the circuit.

Attributes

geq

Return whether the comparator compares greater or less equal.

Returns

True, if the comparator compares >=, False if <.

num_state_qubits

The number of qubits encoding the state for the comparison.

Returns

The number of state qubits.

value

The value to compare the qubit register to.

Returns

The value against which the value of the qubit register is compared.

name

Type: str

A human-readable name for the circuit.

Example

from qiskit import QuantumCircuit
 
qc = QuantumCircuit(2, 2, name="my_circuit")
print(qc.name)

my_circuit