Dax Fohl

**Description of the issue** Density matrix is mentioned in docstrings for `_BufferedStateVector`, `SimulationState._perform_measurement`, and `Simulator`. Should be changed to "state vector" and `QuantumStateRepresentation` respectively.

Move from mypy to better type checker

2

**Description of the issue** Newer type checkers, such as pyright, pytype, pyre are faster, able to infer types implicitly, and catch more errors. Pyright in particular is also incremental, so...

Add CY and CCY gates

7

## Is your feature request related to a use case or problem? Please explain I noticed the issue when reviewing the qelib1.inc PR and while working on controlled gate decomposition....

DecompositionContext is never None

4

In `decompose_protocol.py`, `"_decompose_with_context_"` is never called without a valid `DecompositionContext`. However, many of the type annotations, both in `decompose_protocol.py` and in `_decompose_with_context_` implementations across the project, specify `context: DecompositionContext |...

Fix classical control diagram symbols and svg

5

Fixes #5688. Fixes #5689. A quick image search for circuit diagrams shows that the convention seems to be arrows for measurement, which I represent here in diagrams with `V`. I...

Preserve cached values in Circuit more granularly

3

This PR improves the resilience of the cached member fields in Circuit. Most importantly, `_placement_cache`, which is used to speed up `Circuit.append()` from O(N) to O(1), is made to be...

Add measurement_keys property

1

This adds `measurement_keys` and `control_keys` properties to `Circuit`, `Gate`, `Operation`, and `Moment`, and any subclasses that require them, as an alternative to the corresponding protocols. These properties are cached for...

PauliGate and PauliString equality works only on odd exponents

8

## Describe the issue There's an inconsistency in how Pauli ops handle exponentiation and multiplication with respect to equality. While equality holds when the exponent is odd, it doesn't when...

Replace "structure" protocols with regular properties

1

## Is your design idea/issue related to a use case or problem? Please explain Mathematical protocols like `unitary` and `channel`, and relational protocols like `commutes` and `act_on` all provide useful...

Optimize circuit construction when Insert is used

1

## Is your feature request related to a use case or problem? Please explain #6882 created a cache that sped up circuit construction if only "append" (or equivalent "insert" at...