How to run Color code on STIM?

Question

I am trying to simulate color code on STIM. I have provided my code below. But I am getting the following error

Traceback (most recent call last)
ValueError: Failed to decompose errors into graphlike components with at most two symptoms.
The error component that failed to decompose is 'D9, D18, D27'.

My code:

color_code_tasks = [
    sinter.Task(
        circuit = stim.Circuit.generated(
            "color_code:memory_xyz",
            rounds=10,
            distance=9,
            before_round_data_depolarization=1e-2,
        ),
    )
]

collected_color_code_stats: List[sinter.TaskStats] = sinter.collect(
    num_workers=4,
    tasks=surface_code_tasks,
    decoders=['pymatching'],
    max_shots=10000,
    max_errors=500,
    print_progress=True,
)

I tried to ignore this error by passing ignore_decomposition_failures=True to stim.Circuit.detector_error_model(...). Here is my modified code:

custom_dem = circuit.detector_error_model(
    decompose_errors=True,
    ignore_decomposition_failures=True,
)

color_code_tasks = [
    sinter.Task(
        circuit = stim.Circuit.generated(
            "color_code:memory_xyz",
            rounds=10,
            distance=9,
            before_round_data_depolarization=1e-2,
        ),
        detector_error_model=custom_dem,
    )
]

collected_color_code_stats: List[sinter.TaskStats] = sinter.collect(
    num_workers=4,
    tasks=surface_code_tasks,
    decoders=['pymatching'],
    max_shots=10000,
    max_errors=500,
    print_progress=True,
)

But this time I am getting another ValueError: circuit.num_detectors=300 != detector_error_model.num_detectors=132

How can I solve this issue?

Answer 1

The custom detector error model you're giving is from a totally different circuit.

Once you fix that, you're going to run into the issue that the decoder you've chosen (pymatching) can't decode color codes. Unfortunately, as far as I know, there aren't any open source color code decoders out there (nevermind one that can be used with sinter), which is a major obstacle to what you're trying to do.