These matrices are the terms in the operator sum representation of
a quantum channel. If the returned matrices are {A_0,A1,..., A{r-1} },
then this describes the channel:
\rho \rightarrow \sum_{k=0}^{r-1} A_0 \rho A0^\dagger
These matrices are required to satisfy the trace preserving condition
\sum{k=0}^{r-1} A_i^\dagger A_i = I
where I is the identity matrix. The matrices A_i are sometimes called
Kraus or noise operators.
Args
val
The value to describe by a channel.
default
Determines the fallback behavior when val doesn't have
a channel. If default is not set, a TypeError is raised. If
default is set to a value, that value is returned.
Returns
If val has a _channel_ method and its result is not NotImplemented,
that result is returned. Otherwise, if val has a _mixture_ method
and its results is not NotImplement a tuple made up of channel
corresponding to that mixture being a probabilistic mixture of unitaries
is returned. Otherwise, if val has a _unitary_ method and
its result is not NotImplemented a tuple made up of that result is
returned. Otherwise, if a default value was specified, the default
value is returned.
Raises
TypeError
val doesn't have a channel or unitary method (or that
method returned NotImplemented) and also no default value was
specified.