  The performance of quantum computers is hindered by decoherence and
crosstalk, which cause errors and limit the ability to perform long
computations. Dynamical decoupling is a technique that alleviates these issues
by applying carefully timed pulses to individual qubits, effectively
suppressing unwanted interactions. However, as quantum devices grow in size, it
becomes increasingly important to minimize the time required to implement
dynamical decoupling across the entire system. Here, we present
``Chromatic-Hadamard Dynamical Decoupling'' (CHaDD), an approach that
efficiently schedules dynamical decoupling pulses for quantum devices with
arbitrary qubit connectivity. By leveraging Hadamard matrices, CHaDD achieves a
circuit depth that scales linearly with the chromatic number of the
connectivity graph for general two-qubit interactions, assuming instantaneous
pulses. This includes ZZ crosstalk, which is prevalent in superconducting qubit
devices. CHaDD's scaling represents an exponential improvement over all
previous multi-qubit decoupling schemes for devices with connectivity graphs
whose chromatic number grows at most polylogarithmically with the number of
qubits. For graphs with a 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.
