Quellcode für qiskit.circuit.delay

# 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.

"""
Delay instruction (for circuit module).
"""
import numpy as np
from qiskit.circuit.exceptions import CircuitError
from qiskit.circuit.instruction import Instruction


class Delay(Instruction):
    """Do nothing and just delay/wait/idle for a specified duration."""

    def __init__(self, duration, unit='dt'):
        """Create new delay instruction."""
        if not isinstance(duration, (float, int)):
            raise CircuitError('Unsupported duration type.')

        if unit == 'dt' and not isinstance(duration, int):
            raise CircuitError("Integer duration is required for 'dt' unit.")

        if unit not in {'s', 'ms', 'us', 'ns', 'ps', 'dt'}:
            raise CircuitError('Unknown unit %s is specified.' % unit)

        super().__init__("delay", 1, 0, params=[duration], unit=unit)

    def inverse(self):
        """Special case. Return self."""
        return self

    def broadcast_arguments(self, qargs, cargs):
        yield [qarg for sublist in qargs for qarg in sublist], []

    def c_if(self, classical, val):
        raise CircuitError('Conditional Delay is not yet implemented.')

    @property
    def duration(self):
        """Get the duration of this delay."""
        return self.params[0]

    @duration.setter
    def duration(self, duration):
        """Set the duration of this delay."""
        self.params = [duration]

    def to_matrix(self) -> np.ndarray:
        """Return the identity matrix."""
        return np.array([[1, 0],
                         [0, 1]], dtype=complex)

    def __repr__(self):
        """Return the official string representing the delay."""
        return "%s(duration=%s[unit=%s])" % \
               (self.__class__.__name__, self.params[0], self.unit)