Source code for mimiqcircuits.operations.gates.generalized.qft
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# Licensed under the Apache License, Version 2.0 (the "License");
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# http://www.apache.org/licenses/LICENSE-2.0
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import mimiqcircuits.operations.gates.gate as mcg
from mimiqcircuits.operations.gates.standard.cphase import GateCP
from mimiqcircuits.operations.gates.standard.hadamard import GateH
import mimiqcircuits.lazy as lz
from symengine import pi
[docs]
class QFT(mcg.Gate):
"""
Quantum Fourier transform.
Performs the quantum Fourier transform on a register of `n` qubits.
Args:
n (int): The number of qubits in the quantum register.
Raises:
ValueError: If the number of qubits is less than 1.
Returns:
QFT: The Quantum Fourier Transform operation.
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(QFT(2),1,2)
3-qubit circuit with 1 instructions:
└── QFT @ q[1,2]
<BLANKLINE>
"""
_name = "QFT"
_num_qregs = 1
_num_qubits = None
def __init__(self, num_qubits):
if num_qubits < 1:
raise ValueError("Number of qubits must be greater than 0")
super().__init__()
self._num_qubits = num_qubits
self._qregsizes = [num_qubits]
self._params = [num_qubits]
def __new__(cls, *args):
if len(args) == 0:
return lz.LazyExpr(QFT, lz.LazyArg())
elif len(args) == 1:
return object.__new__(cls)
else:
raise ValueError("Invalid number of arguments.")
def _matrix(self):
raise NotImplementedError(
"Matrix representation for Quantum Fourier Transform is not implemented.")
def _decompose(self, circ, qubits, bits):
q = qubits[::-1]
circ.push(GateH(), q[0])
for i in range(1, self.num_qubits):
for j in range(i):
angle = pi / (2.0**(i-j))
circ.push(GateCP(angle), q[i], q[j])
circ.push(GateH(), q[i])
return circ
__all__ = ['QFT']