Source code for mimiqcircuits.operations.gates.generalized.phasegradient

#
# Copyright © 2022-2023 University of Strasbourg. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
#

import mimiqcircuits.operations.gates.gate as mcg
from mimiqcircuits.operations.gates.standard.phase import GateP
import mimiqcircuits.lazy as lz
from symengine import pi




class PhaseGradient(mcg.Gate):
    """
    Phase Gradient gate

    A phase gradient gate applies a phase shift to a quantum register of `n` qubits,
    where each computational basis state `|k⟩` experiences a phase
    proportional to its integer value `k`

    Args:
        n (int): The number of qubits in the quantum register.

    Returns:
        PhaseGradient: The PhaseGradient gate.

    Attributes:
        name (str): The name of the operation.
        num_qubits (int): The number of qubits in the quantum register.
        qregsizes (list of int): The sizes of the quantum registers.

    Examples:
        >>> from mimiqcircuits import *
        >>> c=Circuit()
        >>> c.push(PhaseGradient(2),9,8)
        10-qubit circuit with 1 instructions:
        └── PhaseGradient @ q[9,8]
        <BLANKLINE>

    """
    _name = "PhaseGradient"
    _num_qregs = 1

    def __init__(self, num_qubits):
        super().__init__()

        self._num_qubits = num_qubits
        self._qregsizes = [num_qubits,]
        self._params = [num_qubits]

        self._num_bits = 0

    def __new__(cls, *args):
        if len(args) == 0:
            return lz.LazyExpr(PhaseGradient, lz.LazyArg())
        elif len(args) == 1:
            return object.__new__(cls)
        else:
            raise ValueError("Invalid number of arguments.")

    def _decompose(self, circ, qubits, bits):
        for i in range(len(qubits) - 1, -1, -1):
            phase = 1 * pi / 2.0**(i)
            circ.push(GateP(phase), qubits[i])
        return circ

    def _matrix(self):
        raise NotImplementedError(
            "Matrix representation for PhaseGradient is not implemented.")



__all__ = ['PhaseGradient']