qiskit.circuit.library.standard_gates.ry のソースコード
# This code is part of Qiskit.
#
# (C) Copyright IBM 2017.
#
# 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.
"""Rotation around the Y axis."""
import math
import numpy
from qiskit.qasm import pi
from qiskit.circuit.controlledgate import ControlledGate
from qiskit.circuit.gate import Gate
from qiskit.circuit.quantumregister import QuantumRegister
[ドキュメント]class RYGate(Gate):
r"""Single-qubit rotation about the Y axis.
**Circuit symbol:**
.. parsed-literal::
┌───────┐
q_0: ┤ Ry(ϴ) ├
└───────┘
**Matrix Representation:**
.. math::
\newcommand{\th}{\frac{\theta}{2}}
RY(\theta) = exp(-i \th Y) =
\begin{pmatrix}
\cos{\th} & -\sin{\th} \\
\sin{\th} & \cos{\th}
\end{pmatrix}
"""
[ドキュメント] def __init__(self, theta, label=None):
"""Create new RY gate."""
super().__init__('ry', 1, [theta], label=label)
def _define(self):
"""
gate ry(theta) a { r(theta, pi/2) a; }
"""
# pylint: disable=cyclic-import
from qiskit.circuit.quantumcircuit import QuantumCircuit
from .r import RGate
q = QuantumRegister(1, 'q')
qc = QuantumCircuit(q, name=self.name)
rules = [
(RGate(self.params[0], pi / 2), [q[0]], [])
]
for instr, qargs, cargs in rules:
qc._append(instr, qargs, cargs)
self.definition = qc
[ドキュメント] def control(self, num_ctrl_qubits=1, label=None, ctrl_state=None):
"""Return a (mutli-)controlled-RY gate.
Args:
num_ctrl_qubits (int): number of control qubits.
label (str or None): An optional label for the gate [Default: None]
ctrl_state (int or str or None): control state expressed as integer,
string (e.g. '110'), or None. If None, use all 1s.
Returns:
ControlledGate: controlled version of this gate.
"""
if num_ctrl_qubits == 1:
gate = CRYGate(self.params[0], label=label, ctrl_state=ctrl_state)
gate.base_gate.label = self.label
return gate
return super().control(num_ctrl_qubits=num_ctrl_qubits, label=label, ctrl_state=ctrl_state)
[ドキュメント] def inverse(self):
r"""Return inverted RY gate.
:math:`RY(\lambda){\dagger} = RY(-\lambda)`
"""
return RYGate(-self.params[0])
[ドキュメント] def to_matrix(self):
"""Return a numpy.array for the RY gate."""
cos = math.cos(self.params[0] / 2)
sin = math.sin(self.params[0] / 2)
return numpy.array([[cos, -sin],
[sin, cos]], dtype=complex)
[ドキュメント]class CRYGate(ControlledGate):
r"""Controlled-RY gate.
**Circuit symbol:**
.. parsed-literal::
q_0: ────■────
┌───┴───┐
q_1: ┤ Ry(ϴ) ├
└───────┘
**Matrix representation:**
.. math::
\newcommand{\th}{\frac{\theta}{2}}
CRY(\theta)\ q_0, q_1 =
I \otimes |0\rangle\langle 0| + RY(\theta) \otimes |1\rangle\langle 1| =
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & \cos{\th} & 0 & -\sin{\th} \\
0 & 0 & 1 & 0 \\
0 & \sin{\th} & 0 & \cos{\th}
\end{pmatrix}
.. note::
In Qiskit's convention, higher qubit indices are more significant
(little endian convention). In many textbooks, controlled gates are
presented with the assumption of more significant qubits as control,
which in our case would be q_1. Thus a textbook matrix for this
gate will be:
.. parsed-literal::
┌───────┐
q_0: ┤ Ry(ϴ) ├
└───┬───┘
q_1: ────■────
.. math::
\newcommand{\th}{\frac{\theta}{2}}
CRY(\theta)\ q_1, q_0 =
|0\rangle\langle 0| \otimes I + |1\rangle\langle 1| \otimes RY(\theta) =
\begin{pmatrix}
1 & 0 & 0 & 0 \\
0 & 1 & 0 & 0 \\
0 & 0 & \cos{\th} & -\sin{\th} \\
0 & 0 & \sin{\th} & \cos{\th}
\end{pmatrix}
"""
[ドキュメント] def __init__(self, theta, label=None, ctrl_state=None):
"""Create new CRY gate."""
super().__init__('cry', 2, [theta], num_ctrl_qubits=1, label=label,
ctrl_state=ctrl_state, base_gate=RYGate(theta))
def _define(self):
"""
gate cry(lambda) a,b
{ u3(lambda/2,0,0) b; cx a,b;
u3(-lambda/2,0,0) b; cx a,b;
}
"""
# pylint: disable=cyclic-import
from qiskit.circuit.quantumcircuit import QuantumCircuit
from .u3 import U3Gate
from .x import CXGate
q = QuantumRegister(2, 'q')
qc = QuantumCircuit(q, name=self.name)
rules = [
(U3Gate(self.params[0] / 2, 0, 0), [q[1]], []),
(CXGate(), [q[0], q[1]], []),
(U3Gate(-self.params[0] / 2, 0, 0), [q[1]], []),
(CXGate(), [q[0], q[1]], [])
]
for instr, qargs, cargs in rules:
qc._append(instr, qargs, cargs)
self.definition = qc
[ドキュメント] def inverse(self):
"""Return inverse CRY gate (i.e. with the negative rotation angle)."""
return CRYGate(-self.params[0], ctrl_state=self.ctrl_state)
[ドキュメント] def to_matrix(self):
"""Return a numpy.array for the CRY gate."""
half_theta = float(self.params[0]) / 2
cos = numpy.cos(half_theta)
sin = numpy.sin(half_theta)
if self.ctrl_state:
return numpy.array([[1, 0, 0, 0],
[0, cos, 0, -sin],
[0, 0, 1, 0],
[0, sin, 0, cos]],
dtype=complex)
else:
return numpy.array([[cos, 0, -sin, 0],
[0, 1, 0, 0],
[sin, 0, cos, 0],
[0, 0, 0, 1]],
dtype=complex)