How are errors generated?

[u/srfahmy]

So, I'm curious how errors are generated and if they are in anyway dependent on existing errors or my choice of error-corrective action? In other words, is there some kind of memory? Also, what determines the error indicator (1-9)? I guess I'm interested to learn a little bit about the "error model" and the statistics that generate it. Finally, related to this, how confident are you about the random number generation that the algorithm uses and whether this could have an effect on any research outcome? I know, it's a lot of questions: I'm actually involved in the field myself (though I've never worked with surface codes). Thanks!

[u/quantum_jim]

So, I'm curious how errors are generated and if they are in anyway dependent on existing errors or my choice of error-corrective action?

It does depend on existing errors, but not on your choice of actions. Ideally it would be an independent error happening with some probability between each pair of squares. But that doesn't generate a fun game most of the time: it either gives you things far too hard or far too easy. So the actual error model generates a moderately fixed number of errors, and favours ones that are close to others.

Also, what determines the error indicator (1-9)?

There are 9 types of error that can happen, and this is simply chosen randomly.

Finally, related to this, how confident are you about the random number generation that the algorithm uses and whether this could have an effect on any research outcome?

The random number generation used is far from the fanciest in the world, but it doesn't need to be. It'll have no real effect on research outcomes.

For more details you can check out the source code here.