surface_sim.models.Model.meas_target

models.Model.meas_target(qubit, rel_meas_ind)

Returns the global measurement index for stim.target_rec for the specified qubit and its relative measurement index (for the given qubit).

Instead of working with global measurement indexing (as stim does), this function allows to work with local measurement indexing for each qubit (see Notes for an example).

Parameters:

qubit

Label of the qubit.

rel_meas_ind

Relative measurement index for the given qubit.

Returns:

GateTarget

Target measurement index (stim.target_rec) for building the detectors and observables.

Notes

To access the first measurement in the following example

M 0
M 1
M 0

one would use -3 in stim’s indexing. However, in the “local measurement indexing for each qubit”, it would correspond to (q0, -2). This makes it easier for building the detectors as they correspond to the XOR of syndrome outcomes (ancilla outcomes) between different QEC rounds (or some linear combination of syndrome outcomes).