Option to dynamically decouple qubits regardless of their state

[dieris]

Summary

Modify behavior of skip_reset_qubits optional argument. If False, dynamical decoupling is applied on qubits regardless of their state, even on delays that are at the beginning of a circuit. This option now matches the behavior in qiskit.

Details and comments

This can be useful to enforce the same DD sequence to be applied throughout a circuit regardless of the qubit state (as determined by the preceding nodes).

[coveralls]

Pull Request Test Coverage Report for Build 8253340646

Details

• 3 of 3 (100.0%) changed or added relevant lines in 2 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.03%) to 43.375%

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Totals
Change from base Build 8099540967:	0.03%
Covered Lines:	2943
Relevant Lines:	6785

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💛 - Coveralls

[ajavadia]

can we make this the same as the dynamical decoupling in qiskit? There the __init__ has an argument skip_reset_qubits which is set to True by default, and setting it to False will instruct the pass to insert DD regardless of qubit state.
https://github.com/Qiskit/qiskit/blob/a7fa6c52a6191034e52ef015378b9fc8cee34a26/qiskit/transpiler/passes/scheduling/dynamical_decoupling.py#L115

[dieris]

That's a good point. I realized that skip_reset_qubits here is already an option, but only enforces DD (when False) if the circuit is actually following a reset, but not on qubits that have delays at the beginning of a circuit (the reason being that those qubits are not marked as dirty). I believe this is different behavior than in qiskit, so it may make more sense to align it here instead of adding include_clean_qubits as a different option.

In other words,
current behavior with skip_reset_qubits = False

Desired behavior:

[ajavadia]

looks good. can you update the PR summary to match the recent change as well