Where is Qiskit's RepetitionCode class now?

Question

Now that Qiskit's ignis module has been deprecated, where does qiskit.ignis.verification.topological_codes.RepetitionCode or its equivalent reside now?

Answer 1

According to the migration guide:

topological_codes will continue development under NCCR-SPIN, while the functionality is reintegrated into Qiskit. Some additional functionality can also be found in the offshoot project qtcodes.

Looking at the NCCR-SPIN repository, we can see that the RepetitionCode is indeed defined there:

class RepetitionCode:
    """
    Implementation of a distance d repetition code, implemented over
    T syndrome measurement rounds.
    """

    def __init__(self, d, T=0, xbasis=False, resets=False, delay=0, barriers=False):
        """
        Creates the circuits corresponding to a logical 0 and 1 encoded
        using a repetition code.
        Args:
            d (int): Number of code qubits (and hence repetitions) used.
            T (int): Number of rounds of ancilla-assisted syndrome measurement.
            xbasis (bool): Whether to use the X basis to use for encoding (Z basis used by default).
            resets (bool): Whether to include a reset gate after mid-circuit measurements.
            delay (float): Time (in dt) to delay after mid-circuit measurements (and delay).
            barrier (bool): Boolean denoting whether to include a barrier at the end.
        Additional information:
            No measurements are added to the circuit if `T=0`. Otherwise
            `T` rounds are added, followed by measurement of the code
            qubits (corresponding to a logical measurement and final
            syndrome measurement round).
        """