Diagnosing quantum crosstalk in superconducting quantum chips by using out-of-time-order correlators

Performance of a scalable quantum processor critically relies on minimizing crosstalk and unwanted interactions within the system, as it is vital for parallel controlled operations on qubits. We present a protocol not only to provide information about residual coupling but also to effectively discriminate it from the influence of classical crosstalk. Our approach utilizes out-of-time-order correlators (OTOCs) as a signal of quantum crosstalk, making it applicable to various coupling forms and scalable architectures. To demonstrate the effectiveness of our protocol, we provide a theoretical analysis and simulate its implementation in coupled superconducting qubits.