Prepare 0.46.1

[kevinhartman]

Summary

Details and comments

[qiskit-bot]

One or more of the the following people are requested to review this:

• @Eric-Arellano
• @javabster
• @Qiskit/terra-core
• @kevinhartman
• @mtreinish

[1ucian0]

There seems to be a flaky test failing that blocked this merged. Therefore:

• I'm checking the root of the problem to see why transpile returns circuits out of the basis set
• I rerun the tests in this branch so it can be merged soon
• I PRed the tests to make them less flaky Seed all the transpile calls in test.python.compiler.test_transpiler #11973

[kevinhartman]

After a bit more investigation, @jakelishman and I have found that the CI failure hit in Windows is actually reproducible on all platforms, but is not introduced in this release (it currently exists in both 0.46.0 as well as the newly released 1.0.2 for example).

Given that it's not newly introduced and hasn't been hit until now, we'll continue with 0.46.1 as is.

(I'll create a bug and cross-reference this PR)

[jakelishman]

The above bug was a manifestation of #11975 - in certain cases, the test in question (test.python.compiler.test_transpiler.TestMultiChipXXXX.test_transpile_target_with_qubits_without_ops_with_routing at optimization_level=3) would have a swap in its chosen layout+routing, and the target had single-direction CXs, so we'd end up calling GateDirection to flip two of the CXs with Hadamards, then the whole block would be 4 CXs, so attempt to be collected.

As of 0.46.1 and 1.0.2, the following block and seed reproduces that failure reliably:

from qiskit import transpile, QuantumCircuit
from qiskit.circuit import library
from qiskit.transpiler import Target, InstructionProperties
target = Target(num_qubits=5)
target.add_instruction(library.XGate(), {(i,): InstructionProperties(error=0.5) for i in range(4)})
target.add_instruction(library.HGate(), {(i,): InstructionProperties(error=0.5) for i in range(4)})
target.add_instruction(
    library.CXGate(),
    {edge: InstructionProperties(error=0.5) for edge in [(0, 1), (1, 2), (2, 0), (2, 3)]},
)
qc = QuantumCircuit(4)
qc.x(0)
qc.cx(0, 1)
qc.cx(0, 2)
qc.cx(1, 3)
qc.cx(0, 3)

transpile(qc, target=target, optimization_level=3, seed_transpiler=57783)