Add loss policies to NoiseConfig to express different kinds of behavior on lost qubits#3302
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orpuente-MS wants to merge 4 commits into
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Add loss policies to NoiseConfig to express different kinds of behavior on lost qubits#3302orpuente-MS wants to merge 4 commits into
NoiseConfig to express different kinds of behavior on lost qubits#3302orpuente-MS wants to merge 4 commits into
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orpuente-MS
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minestarks and
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billti
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billti
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Jun 13, 2026
| @pytest.mark.parametrize("sim_type", LOSS_POLICY_SIM_TYPES) | ||
| def test_on_loss_swap_skip_keeps_state_but_swaps_loss_flag(sim_type): | ||
| # Overriding `swap.on_loss` to SKIP skips the SWAP unitary, but the loss | ||
| # flag is still exchanged. qs[0] keeps its reset |0> and qs[1] becomes lost. |
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This one is interesting. Worth discussing more. Seems odd you would skip the unitary (which swaps the state) but still swap which is lost. Not sure if that would be physically possible.
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Mmh, maybe the behavior here should be:
SKIPdoesn't apply the unitary nor exchanges loss flags.APPLY_ANYWAYapplies the unitary and exchanges the loss flags.
billti
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Jun 13, 2026
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Jun 13, 2026
| if (shot.qubit_state[q1].heat == -1.0) { | ||
| return true; | ||
| } | ||
| let is_2q = (op.id == OPID_CX || op.id == OPID_CY || op.id == OPID_CZ || |
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You already have is_1q_op defined (line 74). Can you just negate that? For now we only have 1q and 2q ops.
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Yes, you are right.
I think we should reorder the OPID constants so that all 1q ops are consecutive numbers. That will make the check cheaper, but it should be its own PR since it's kind of risky.
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With this change, users are able to specify how gates should behave if at least one of their qubit operands is lost. Below is a comprehensive example, showing all 5 loss policies.