Source code for netket.hilbert.qubit
# Copyright 2021 The NetKet Authors - 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.
from typing import Optional, Union, List
from netket.graph import AbstractGraph
from .homogeneous import HomogeneousHilbert
from ._deprecations import graph_to_N_depwarn
class Qubit(HomogeneousHilbert):
r"""Hilbert space obtained as tensor product of local qubit states."""
[docs] def __init__(self, N: int = 1, graph: Optional[AbstractGraph] = None):
r"""Initializes a qubit hilbert space.
Args:
N: Number of qubits.
graph: (deprecated) a graph from which to extract the number of sites.
Examples:
Simple spin hilbert space.
>>> from netket.hilbert import Qubit
>>> hi = Qubit(N=100)
>>> print(hi.size)
100
"""
N = graph_to_N_depwarn(N=N, graph=graph)
super().__init__([0.0, 1.0], N)
def __pow__(self, n):
return Qubit(self.size * n)
def _mul_sametype_(self, other):
assert type(self) == type(other)
return Qubit(self.size + other.size)
[docs] def ptrace(self, sites: Union[int, List]) -> Optional["Qubit"]:
if isinstance(sites, int):
sites = [sites]
for site in sites:
if site < 0 or site >= self.size:
raise ValueError(
f"Site {site} not in this hilbert space of site {self.size}"
)
Nsites = len(sites)
if self.size - Nsites == 0:
return None
else:
return Qubit(N=self.size - Nsites)
def __repr__(self):
return "Qubit(N={})".format(self._size)
@property
def _attrs(self):
return (self.size,)