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

What is happening?

The example for the plot_bloch_multivector doc looks broken - https://qiskit.org/documentation/stubs/qiskit.visualization.plot_bloch_multivector.html#qiskit.visualization.plot_bloch_multivector

The example is trying to visualize a bell state and the entanglement isn't clearly visualizable with bloch sphere

Is your feature request related to a use case or problem? Please describe.
The only place that uses atol in that function is cirq.linalg.linalg.allclose_up_to_global_phase and it too takes in a default atol.

Describe the solution you'd like
Make atol an optional argument for assert_circuits_with_terminal_measurements_are_equivalent.

**[optional] Describe alternatives/work

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

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

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

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'