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# Source code for qiskit.pulse.instructions.frequency

# This code is part of Qiskit.
#
# (C) Copyright IBM 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.

"""Frequency instructions module. These instructions allow the user to manipulate
the frequency of a channel.
"""
from typing import Optional, Union, Tuple

from qiskit.circuit.parameterexpression import ParameterExpression
from qiskit.pulse.channels import PulseChannel
from qiskit.pulse.instructions.instruction import Instruction
from qiskit.pulse.exceptions import PulseError

[docs]class SetFrequency(Instruction):
r"""Set the channel frequency. This instruction operates on PulseChannel s.
A PulseChannel creates pulses of the form

.. math::
Re[\exp(i 2\pi f jdt + \phi) d_j].

Here, :math:f is the frequency of the channel. The instruction SetFrequency allows
the user to set the value of :math:f. All pulses that are played on a channel
after SetFrequency has been called will have the corresponding frequency.

The duration of SetFrequency is 0.
"""

def __init__(
self,
frequency: Union[float, ParameterExpression],
channel: PulseChannel,
name: Optional[str] = None,
):
"""Creates a new set channel frequency instruction.

Args:
frequency: New frequency of the channel in Hz.
channel: The channel this instruction operates on.
name: Name of this set channel frequency instruction.
"""
super().__init__(operands=(frequency, channel), name=name)

def _validate(self):
"""Called after initialization to validate instruction data.

Raises:
PulseError: If the input channel is not type :class:PulseChannel.
"""
if not isinstance(self.channel, PulseChannel):
raise PulseError(f"Expected a pulse channel, got {self.channel} instead.")

@property
def frequency(self) -> Union[float, ParameterExpression]:
"""New frequency."""
return self.operands[0]

@property
def channel(self) -> PulseChannel:
"""Return the :py:class:~qiskit.pulse.channels.Channel that this instruction is
scheduled on.
"""
return self.operands[1]

@property
def channels(self) -> Tuple[PulseChannel]:
"""Returns the channels that this schedule uses."""
return (self.channel,)

@property
def duration(self) -> int:
"""Duration of this instruction."""
return 0

[docs]class ShiftFrequency(Instruction):
"""Shift the channel frequency away from the current frequency."""

def __init__(
self,
frequency: Union[float, ParameterExpression],
channel: PulseChannel,
name: Optional[str] = None,
):
"""Creates a new shift frequency instruction.

Args:
frequency: Frequency shift of the channel in Hz.
channel: The channel this instruction operates on.
name: Name of this set channel frequency instruction.
"""
super().__init__(operands=(frequency, channel), name=name)

def _validate(self):
"""Called after initialization to validate instruction data.

Raises:
PulseError: If the input channel is not type :class:PulseChannel.
"""
if not isinstance(self.channel, PulseChannel):
raise PulseError(f"Expected a pulse channel, got {self.channel} instead.")

@property
def frequency(self) -> Union[float, ParameterExpression]:
"""Frequency shift from the set frequency."""
return self.operands[0]

@property
def channel(self) -> PulseChannel:
"""Return the :py:class:~qiskit.pulse.channels.Channel that this instruction is
scheduled on.
"""
return self.operands[1]

@property
def channels(self) -> Tuple[PulseChannel]:
"""Returns the channels that this schedule uses."""
return (self.channel,)

@property
def duration(self) -> int:
"""Duration of this instruction."""
return 0