Source code for qailab.circuit.layer_blocks.entanglers

 1"""Different implementations of qubit entangling sections for variational circuits."""
 2from qiskit import QuantumCircuit
 3from qailab.circuit.base import EntanglingBlock
 4
 5


[docs]
 6class CXEntangler(EntanglingBlock):
 7    """
 8                        ┌───┐
 9    q_0: ──■────────────┤ X ├
10         ┌─┴─┐          └─┬─┘
11    q_1: ┤ X ├──■─────────┼──
12         └───┘┌─┴─┐       │
13    q_2: ─────┤ X ├──■────┼──
14    ..        └───┘┌─┴─┐  │
15    q_n: ──────────┤ X ├──■──
16                   └───┘
17    """
18
19    def __init__(self) -> None:
20        super().__init__('CXEntangler')
21
22    def _build_circuit(self, num_qubits: int) -> QuantumCircuit:
23        circuit = QuantumCircuit(num_qubits)
24        for i in range(1, num_qubits):
25            circuit.cx(i-1, i)
26
27        circuit.cx(num_qubits-1, 0)
28        return circuit