Efficient Chromatic-Number-Based Multi-Qubit Decoherence and Crosstalk Suppression

The performance of quantum computers is hindered by decoherence and crosstalk, which cause errors and limit the ability to perform long computations. Dynamical decoupling (DD) alleviates these issues by applying carefully timed pulses to individual qubits, effectively suppressing unwanted interactions. As quantum devices grow in size, it becomes increasingly important to minimize the time required to implement DD across the entire system. We present "Chromatic-Hadamard Dynamical Decoupling" (CHaDD), an approach that efficiently schedules DD pulses for quantum devices with arbitrary qubit connectivity, achieving a circuit depth that scales linearly with the chromatic number of the connectivity graph for general two-qubit interactions, including ZZ crosstalk, which is prevalent in superconducting qubit devices. This scaling represents an exponential improvement over all previous multi-qubit DD schemes for devices with connectivity graphs whose chromatic number grows at most polylogarithmically with the number of qubits. For graphs with constant chromatic number, CHaDD's scaling is independent of the number of qubits. Our results suggest that CHaDD can become a useful tool for enhancing the performance and scalability of quantum computers by efficiently suppressing decoherence and crosstalk across large qubit arrays.