Circuit-based erasure simulation using stim

Question

I want to simulate erasures in a surface code using stim, assuming that any gate on the data qubits can cause an erasure. If I induce erasure after each gate by the method described in How do I perform an erasure error in stim?, the loss-ancilla can be flipped an even number of times, making the even number of erasures on the same qubit unheralded. On the other hand, if I add a different loss-ancilla to any gate, it looks like over-heralding the erasure since it gives information on the specific gate where the loss occurred. Any idea?

Answer 1

Use a different ancilla for each erasure error, or reset the ancilla before each erasure error.

Note that now that PAULI_CHANNEL_2 exists, it's much easier to simultaneously apply the same "if this qubit was hurt, that ancilla was flipped" noise to many pairs of qubits (compared to using ELSE_CORRELATED_ERROR).