Quantum Crosstalk Mitigating Optimized Single Qubit Gates

As we enter the NISQ era, quantum computation is still held back by noise experienced on hardware which is often difficult to mitigate. A particularly important and complex type of noise is crosstalk. In this work, we construct optimized control sequences for two-qubits that suppress crosstalk noise for given gates and crosstalk coupling strength. We utilize the Filter Function Formalism (FFF) to convert a problem of control into one of finding optimized filters. This allows us to analytically derive favorable initial conditions, which are used in the FGRAFS code to find optimal filters using gradient ascent. We obtain simultaneous single qubit control gates on two qubits of 1e-9 infidelity after O(100) iterations of the optimizer. Additionally, we find clear bandwidth control conditions that must be satisfied in order to achieve high fidelity gates for both high pass and bandpass filters.