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Comparators

The following comparators are supported:
  • Equal (denoted as ’==’)
  • NotEqual (denoted as ’!=’)
  • GreaterThan (denoted as ’>’)
  • GreaterEqual (denoted as ’>=’)
  • LessThan (denoted as ’<’)
  • LessEqual (denoted as ’<=’)
Note that integer and fixed-point numbers are represented in a 2-complement method during function evaluation. The binary number is extended in the case of a register size miss-match. For example, the positive signed number (110)2=6(110)_2=6 is expressed as (00110)2(00110)_2 when operating with a 5-qubit register. Similarly, the negative signed number (110)2=−2(110)_2=-2 is expressed as (11110)2(11110)_2. Examples: (5 <= 3) = 0 (5 == 5) = 1 ((011)2(011)_2 == (11)2(11)_2) = 1 (signed (101)2(101)_2 < unsigned (101)2(101)_2) = 1

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Examples

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Example 1: Comparing Two Quantum Variables

This example generates a quantum program that performs ‘equal’ between two variables. The left arg is a signed variable with 5 qubits and the right arg is an unsigned varialbe with 3 qubits. 
from classiq import *


@qfunc
def main(a: Output[QNum], b: Output[QNum], res: Output[QNum]) -> None:
    allocate(5, True, 0, a)
    allocate(3, False, 0, b)

    res |= a == b


qmod = create_model(main)


qprog = synthesize(qmod)

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Example 2: Comparing Integer and Quantum Variable

This example generates a quantum program that performs ‘less equal’ between a quantum register and an integer. The left arg is an unsigned quantum variable with 3 qubits, and the right arg is an integer equal to 
@qfunc
def main(a: Output[QNum], res: Output[QNum]) -> None:
    allocate(3, a)
    hadamard_transform(a)
    res |= a <= 2


qmod = create_model(main)


qprog = synthesize(qmod)

result = execute(qprog).result_value()
result.parsed_counts
Output:
[{'a': 4.0, 'res': 0.0}: 150,
   {'a': 1.0, 'res': 1.0}: 138,
   {'a': 7.0, 'res': 0.0}: 132,
   {'a': 2.0, 'res': 1.0}: 126,
   {'a': 6.0, 'res': 0.0}: 123,
   {'a': 3.0, 'res': 0.0}: 115,
   {'a': 5.0, 'res': 0.0}: 110,
   {'a': 0.0, 'res': 1.0}: 106]