Source code for netket.operator._abstract_super_operator
# 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
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# See the License for the specific language governing permissions and
# limitations under the License.
import numpy as np
import jax.numpy as jnp
from netket.hilbert import DoubledHilbert, AbstractHilbert
from ._discrete_operator import DiscreteOperator
[docs]
class AbstractSuperOperator(DiscreteOperator):
"""
Generic base class for super-operators acting on the tensor product (DoubledHilbert)
space ℋ⊗ℋ, where ℋ is the physical space.
Behaves on :ref:`netket.vqs.VariationalMixedState` as normal operators behave
on :ref:`netket.vqs.VariationalState`.
Cannot be used to act upon pure states.
"""
[docs]
def __init__(self, hilbert):
"""
Initialize a super-operator by passing it the physical hilbert space on which it acts.
This init method constructs the doubled-hilbert space and pass it down to the fundamental
abstractoperator.
"""
super().__init__(DoubledHilbert(hilbert))
@property
def hilbert_physical(self) -> AbstractHilbert:
"""The physical hilbert space on which this super-operator acts."""
return self.hilbert.physical
[docs]
def to_qobj(self): # -> "qutip.Qobj"
raise NotImplementedError("Superoperator to Qobj not yet implemented")
def __matmul__(self, other):
# Override DiscreteOperator to implement the Squared trick.
# Should eventually remove it as well.
if isinstance(other, np.ndarray) or isinstance(other, jnp.ndarray):
return self.apply(other)
elif isinstance(other, AbstractSuperOperator):
if self == other and self.is_hermitian:
from ._lazy import Squared
return Squared(self)
else:
return self._op__matmul__(other)
else:
return NotImplemented
def __rmatmul__(self, other):
# override DiscreteOperator to implement the Squared trick.
# Should eventually remove it as well.
if isinstance(other, np.ndarray) or isinstance(other, jnp.ndarray):
return NotImplemented
elif isinstance(other, AbstractSuperOperator):
if self == other and self.is_hermitian:
from ._lazy import Squared
return Squared(self)
else:
return self._op__rmatmul__(other)
else:
return NotImplemented