def _tensor_product(self, other, reverse=False):
"""Return the tensor product channel.
Args:
other (QuantumChannel): a quantum channel.
reverse (bool): If False return self ⊗ other, if True return
if True return (other ⊗ self) [Default: False
Returns:
Choi: the tensor product channel as a Choi object.
Raises:
QiskitError: if other is not a QuantumChannel subclass.
"""
# Convert other to Choi
if not isinstance(other, Choi):
other = Choi(other)
if reverse:
input_dims = self.input_dims() + other.input_dims()
output_dims = self.output_dims() + other.output_dims()
data = _bipartite_tensor(other.data,
self._data,
shape1=other._bipartite_shape,
shape2=self._bipartite_shape)
else:
input_dims = other.input_dims() + self.input_dims()
output_dims = other.output_dims() + self.output_dims()
data = _bipartite_tensor(self._data,
other.data,
shape1=self._bipartite_shape,
shape2=other._bipartite_shape)
return Choi(data, input_dims, output_dims)
def _tensor_product(self, other, reverse=False):
"""Return the tensor product channel.
Args:
other (QuantumChannel): a quantum channel.
reverse (bool): If False return self ⊗ other, if True return
if True return (other ⊗ self) [Default: False
Returns:
SuperOp: the tensor product channel as a SuperOp object.
Raises:
QiskitError: if other cannot be converted to a channel.
"""
# Convert other to SuperOp
if not isinstance(other, SuperOp):
other = SuperOp(other)
if reverse:
input_dims = self.input_dims() + other.input_dims()
output_dims = self.output_dims() + other.output_dims()
data = _bipartite_tensor(
other.data,
self._data,
shape1=other._bipartite_shape,
shape2=self._bipartite_shape)
else:
input_dims = other.input_dims() + self.input_dims()
output_dims = other.output_dims() + self.output_dims()
data = _bipartite_tensor(
self._data,
other.data,
shape1=self._bipartite_shape,
shape2=other._bipartite_shape)
return SuperOp(data, input_dims, output_dims)
def _tensor(cls, a, b):
ret = copy.copy(a)
ret._op_shape = a._op_shape.tensor(b._op_shape)
ret._data = _bipartite_tensor(a._data, b.data,
shape1=a._bipartite_shape,
shape2=b._bipartite_shape)
return ret
def expand(self, other):
"""Return the tensor product channel other ⊗ self.
Args:
other (QuantumChannel): a quantum channel.
Returns:
Choi: the tensor product channel other ⊗ self as a Choi object.
Raises:
QiskitError: if other cannot be converted to a channel.
"""
# Convert other to Choi
if not isinstance(other, Choi):
other = Choi(other)
input_dims = self.input_dims() + other.input_dims()
output_dims = self.output_dims() + other.output_dims()
data = _bipartite_tensor(other.data,
self._data,
shape1=other._bipartite_shape,
shape2=self._bipartite_shape)
return Choi(data, input_dims, output_dims)
def tensor(self, other):
"""Return the tensor product channel self ⊗ other.
Args:
other (QuantumChannel): a quantum channel.
Returns:
SuperOp: the tensor product channel self ⊗ other as a SuperOp
object.
Raises:
QiskitError: if other cannot be converted to a channel.
"""
# Convert other to SuperOp
if not isinstance(other, SuperOp):
other = SuperOp(other)
input_dims = other.input_dims() + self.input_dims()
output_dims = other.output_dims() + self.output_dims()
data = _bipartite_tensor(self._data,
other.data,
shape1=self._bipartite_shape,
shape2=other._bipartite_shape)
return SuperOp(data, input_dims, output_dims)
