English
Languages
English
Bengali
French
German
Japanese
Korean
Portuguese
Spanish
Tamil

Source code for qiskit.circuit.library.standard_gates.iswap

# This code is part of Qiskit.
#
# (C) Copyright IBM 2017, 2020.
#
# This code is licensed under the Apache License, Version 2.0. You may
# obtain a copy of this license in the LICENSE.txt file in the root directory
# of this source tree or at http://www.apache.org/licenses/LICENSE-2.0.
#
# Any modifications or derivative works of this code must retain this
# copyright notice, and modified files need to carry a notice indicating
# that they have been altered from the originals.

"""iSWAP gate."""

from typing import Optional
import numpy as np
from qiskit.circuit.gate import Gate
from qiskit.circuit.quantumregister import QuantumRegister


[docs]class iSwapGate(Gate): r"""iSWAP gate. A 2-qubit XX+YY interaction. This is a Clifford and symmetric gate. Its action is to swap two qubit states and phase the :math:`|01\rangle` and :math:`|10\rangle` amplitudes by i. Can be applied to a :class:`~qiskit.circuit.QuantumCircuit` with the :meth:`~qiskit.circuit.QuantumCircuit.iswap` method. **Circuit Symbol:** .. parsed-literal:: q_0: ─⨂─ q_1: ─⨂─ **Reference Implementation:** .. parsed-literal:: ┌───┐┌───┐ ┌───┐ q_0: ┤ S ├┤ H ├──■──┤ X ├───── ├───┤└───┘┌─┴─┐└─┬─┘┌───┐ q_1: ┤ S ├─────┤ X ├──■──┤ H ├ └───┘ └───┘ └───┘ **Matrix Representation:** .. math:: iSWAP = R_{XX+YY}\left(-\frac{\pi}{2}\right) = \exp\left(i \frac{\pi}{4} \left(X{\otimes}X+Y{\otimes}Y\right)\right) = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 0 & i & 0 \\ 0 & i & 0 & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix} This gate is equivalent to a SWAP up to a diagonal. .. math:: iSWAP = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix} . \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & i & 0 & 0 \\ 0 & 0 & i & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix} """ def __init__(self, label: Optional[str] = None): """Create new iSwap gate.""" super().__init__("iswap", 2, [], label=label) def _define(self): """ gate iswap a,b { s q[0]; s q[1]; h q[0]; cx q[0],q[1]; cx q[1],q[0]; h q[1]; } """ # pylint: disable=cyclic-import from qiskit.circuit.quantumcircuit import QuantumCircuit from .h import HGate from .s import SGate from .x import CXGate q = QuantumRegister(2, "q") qc = QuantumCircuit(q, name=self.name) rules = [ (SGate(), [q[0]], []), (SGate(), [q[1]], []), (HGate(), [q[0]], []), (CXGate(), [q[0], q[1]], []), (CXGate(), [q[1], q[0]], []), (HGate(), [q[1]], []), ] for instr, qargs, cargs in rules: qc._append(instr, qargs, cargs) self.definition = qc def __array__(self, dtype=None): """Return a numpy.array for the iSWAP gate.""" return np.array([[1, 0, 0, 0], [0, 0, 1j, 0], [0, 1j, 0, 0], [0, 0, 0, 1]], dtype=dtype)