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

According to the official docs:

"The action of a __slots__ declaration is limited to the class where it is defined. As a result, subclasses will have a __dict__ unless they also define __slots__ (which must only contain names of any additional slots)."

What is the expected enhancement?

All subclasses down the inheritance chain (Qubit, Clbit, AncillaQubit) ought to define:

Is your feature request related to a use case or problem? Please describe.
Right now a lot of modules (in particular tests) are pretty free form with how they do imports. It's a good practice to import modules wherever possible.

bad:

from cirq.devices import GridQubit

good:

from cirq import devices

devices.GridQubit(whatever)

**Describe the soluti

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

The grammar was extended with some built-in math functions that were out of the specification. TSC decided that the functions included in Qiskit/openqasm#275 should be part of the specification.

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

The formulas at API page for https://docs.microsoft.com/en-us/qsharp/api/qsharp/microsoft.quantum.preparation.purifiedmixedstatewithdata are also broken, but I couldn't figure out what caused it at a glance.

Originally posted by @tcNickolas in microsoft/QuantumLibraries#484 (comment)

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'