quantum-computing

Several katas could have better error messaging:

• Superposition : the test harness could log the actual state of the system after prep vs the expected state before asserting that they are the same (the change would add state prep and logging using DumpMachine to AssertEqualOnZeroState)
• BasicGates : a similar improvement, but a bit more extra code to write a unified test wrapper

Here are some examples:

• Root README is missing machine learning category of samples
• README in algorithms is missing repeat-until-success and sudoku-grover
• [README in diagnostics](https://github.com/microsoft/Quantum/blob/main/samples/diagnostics/RE

Environment

• Qiskit Terra version: 0.19.1
• Python version: 3.8
• Operating system: Ubuntu 18.04.6 LTS

What is happening?

The binding of the angle parameter of the C3XGate doesn't work as expected.
If we parametrize the C3XGate with an angle parameter as in the signature in the doc `C3XGate(a

Description of the issue
cirq.two_qubit_matrix_to_operations decomposes a 2q unitary matrix into CZs + single qubit rotations. The method was originally written when we had only decomposition into CZs. But now, we have other analytical decompositions like cirq.two_qubit_matrix_to_sqrt_iswap_operations, cirq.two_qubit_matrix_to_ion_operations etc.

We should do the following renames (

To get this codebase up to standard, we need to add type hints. At the very least, perhaps we should start insisting that all new code has type hints added, but moreover we need to add typing to the code that currently exists.

This is a pretty large project, but luckily it can be done incrementally - I believe at this point it's a stretch goal for v1, if anyone wants to help it would be much ap

Feature details

Due to the similarity, it is easy to confuse qml.X and qml.PauliX, especially since other methods of specifying circuits, e.g., QASM, use x for PauliX. But if a user uses qml.X in their circuit on a qubit device, nothing happens to inform them that the incorrect operation is being used:

@qml.qnode(dev)
def circ():
    qml.PauliX(wires=0)
    qml.Hada

Is your feature request related to a problem? Please describe.
The dimension argument of qutip operators are quite inconsistent in the naming, type and description. Here are a few examples picked from the functions doc page:

• basis > dimensions: int or list of ints _Number of Fock states in Hilbert space. If a list, then

What is the expected enhancement?

The openQASM project should have release notes associated with each tagged release (see #321). These should contain a summary of all changes included in the prepared release (or the development branch). For ease (and distribution) of maintenance, we should consider using reno which has been used with success in Qiski

Describe the Issue

1. In section 2.4.3 on Controlled Rotations, the line "A controlled R_x(θ) could similarly be made using CNOT gates." seems incorrect.
2. I assume that the line claims that replacing R_y(θ/2) by R_x(θ/2) (similarly for the -θ case), in the circuit above, we would get a controlled R_x(θ). This is incorrect.
3. Passing |1> through q_0, we get X R_x(-θ/2) X R_x(θ/2)q_1, fo

Is your feature request related to a problem? Please describe.
Adding concrete examples to API documentation comments can help clarify how Q# functions and operations are to be used. For example, the documentation for Microsoft.Quantum.Arrays.ElementsAt lists how the function acts on a variety of arrays:

right now, absolute jumps are conflated in the label object here. I'd prefer we instead introduce a new object called absolute-program-location or something like that. (I don't want to use "address" only because it feels too dishonest.) If we do this, then we'd change patch-labels to not overwrite these label objects, and we'