English
Languages
English
Bengali
French
German
Japanese
Korean
Portuguese
Spanish
Tamil

# Source code for qiskit.circuit.library.standard_gates.i

# This code is part of Qiskit.
#
#
# obtain a copy of this license in the LICENSE.txt file in the root directory
#
# 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.

"""Identity gate."""

from typing import Optional
import numpy
from qiskit.circuit.gate import Gate

[docs]class IGate(Gate):
r"""Identity gate.

Identity gate corresponds to a single-qubit gate wait cycle,
and should not be optimized or unrolled (it is an opaque gate).

Can be applied to a :class:~qiskit.circuit.QuantumCircuit
with the :meth:~qiskit.circuit.QuantumCircuit.i and
:meth:~qiskit.circuit.QuantumCircuit.id methods.

**Matrix Representation:**

.. math::

I = \begin{pmatrix}
1 & 0 \\
0 & 1
\end{pmatrix}

**Circuit symbol:**

.. parsed-literal::
┌───┐
q_0: ┤ I ├
└───┘
"""

def __init__(self, label: Optional[str] = None):
"""Create new Identity gate."""
super().__init__("id", 1, [], label=label)

[docs]    def inverse(self):
"""Invert this gate."""
return IGate()  # self-inverse

def __array__(self, dtype=None):
"""Return a numpy.array for the identity gate."""
return numpy.array([[1, 0], [0, 1]], dtype=dtype)

[docs]    def power(self, exponent: float):
"""Raise gate to a power."""
return IGate()