Abstract: This disclosure relates to quantum computing systems including a quantum processor that implements one or more operations on multiple qubits and a distributed data processing system programmed to perform calculations to determine control sequences that, when applied to the quantum processor, reduces decoherence, decoherence-induced errors, and control-imperfection-induced errors on the one or more operations on the multiple qubits. A user interface device remote from the distributed data processing system receives from a user of the quantum processor characteristics of the quantum processor including operational constraints and/or desired performance, and sends the characteristics to the data processing system to cause the data processing system to perform the calculations to determine the control sequence based on the characteristics.

Abstract: This disclosure relates to evaluating and improving performance of a control implementation on a quantum processor comprising multiple qubits in the presence of noise. A noise model decomposes noise interactions described by a multi-qubit noise Hamiltonian into multiple contributory noise channels. Each channel generates noise dynamics described by a unique noise-axis operator. For a given control implementation, a unique filter function represents susceptibility of the multi-qubit system to the associated noise dynamics. The filter functions are based on a frequency transformation of the noise axis operator of the corresponding noise channel to thereby evaluate the performance of the control implementation. An optimised control sequence is based on the filter function to reduce the susceptibility of the multi-qubit system to the noise channels, thereby reducing the effective interaction with the multi-qubit noise Hamiltonian.