Abstract: A system and method for indicating, via a heralding signal, that an amplitude damping decay event has occurred within a quantum low-density parity-check code is disclosed. Logical information may be encoded into a superconducting qubit using one or more transmons, wherein a first level and a second level are encoded into a code space of the qubit, and at least one intermediate level outside of the code space characterizes an amplitude damping decay channel which is then used to herald an amplitude damping decay event. Dynamical decoupling pulse sequences may be used to drive such qubit structures and bias noise towards the amplitude damping decay channel. The one or more heralding signals within a lower-level code may then be used as input to a quantum low-density parity-check code for decoding syndrome measurements with the knowledge of occurrences of amplitude damping decay as indicated via the one or more heralding signals.

Abstract: A system and method for indicating, via a heralding signal, that an amplitude damping decay event has occurred within a quantum low-density parity-check (LDPC) code is disclosed. Logical information may be encoded into a superconducting qubit using one or more transmons, wherein a first level and a second level are encoded into a code space of the qubit, and at least one intermediate level outside of the code space characterizes an amplitude damping decay channel which is then used to herald an amplitude damping decay event. Dynamical decoupling pulse sequences may be used to drive such qubit structures and bias noise towards the amplitude damping decay channel. The one or more heralding signals within a lower-level code may then be used as input to a quantum LDPC code for decoding syndrome measurements with the knowledge of occurrences of amplitude damping decay as indicated via the one or more heralding signals.