Add qml.matrix(op) function
#2241
Conversation
|
Hello. You may have forgotten to update the changelog!
|
Codecov Report
@@ Coverage Diff @@
## master #2241 +/- ##
=======================================
Coverage 99.28% 99.28%
=======================================
Files 233 235 +2
Lines 18808 18831 +23
=======================================
+ Hits 18673 18696 +23
Misses 135 135
Continue to review full report at Codecov.
|
josh146
added
the
review-ready 👌
|
|
||
|
|
||
| @qml.op_transform | ||
| def matrix(op, *, wire_order=None): |
There was a problem hiding this comment.
If this can take tapes etc, would you not call it obj?
There was a problem hiding this comment.
Oh, because the wrapper makes sure that by the time it reaches the code in this function, it is an op?
There was a problem hiding this comment.
Yep exactly :) But the documentation will only show the docstring for the first one, hence why I've tried to keep all the information for op/tape/qfunc etc in a single docstring
| Returns: | ||
| tensor_like or function: Function which accepts the same arguments as the QNode or quantum | ||
| function. When called, this function will return the unitary matrix in the appropriate | ||
| autodiff framework (Autograd, TensorFlow, PyTorch, JAX) given its parameters. |
There was a problem hiding this comment.
These are two very different return options. Maybe at least describe the other one, since the explanation just talks about the function return type.
There was a problem hiding this comment.
Sorry, which one do you mean to describe here? Just the functional one?
There was a problem hiding this comment.
Hmm, it can return a tensor or a function, hey? It would be good to say "the tensor is the desired matrix; if a function then it accepts..." or so?
| @pytest.mark.parametrize("op_class", one_qubit_no_parameter) | ||
| def test_non_parametric_gates_qfunc(self, op_class): | ||
| """Verify that the matrices of non-parametric one qubit gates is correct | ||
| when provided as a qfunc""" |
There was a problem hiding this comment.
I may be blind, but it's more provided as a class, not a qfunc, no?
There was a problem hiding this comment.
instantiating an operator is basically the same thing, from PL's point of view, as a qfunc that only queues a single operation 😆 Which is very useful way of thinking when writing the tests
|
|
||
| @pytest.mark.xfail( | ||
| reason="This test will fail because Hamiltonians are not queued to tapes yet!" | ||
| ) |
There was a problem hiding this comment.
yes, I didn't realize this was the case either! something we should really fix.
Co-authored-by: Maria Schuld <mariaschuld@gmail.com>
…to matrix-function
|
Extra awesome that |
Context:
Currently, to get the matrix of an operator, you must do
op.get_matrix(). Alternatively, to get the matrix of a tape/qfunc, you must doqml.transforms.get_unitary_matrix().However, there are many downsides to this:
op.get_matrix()is temporary, and we want to limit users relying on operator methods!qml.transforms.get_unitary_matrix()is hard to find, and also will fail if not all operations on the tape supportget_matrix().It would be nice if there was a single function that covered this singular functionality, while insulating the
op.get_matrix()method from changes.Description of the Change:
Adds
qml.matrix()This function works on operations, qfuncs, tapes, and QNodes.
It accepts wire ordering.
Benefits: As above.
Possible Drawbacks: n/a
Related GitHub Issues: n/a