Robust optimal control for a systematic error in the control amplitude

In the NISQ era, physical qubits coherence time and high fidelity gates are essential to the func-

tioning of quantum computers. In this work we demonstrate, theoretically and experimentally, that

pulses designed by optimisation can be used to counteract the loss of fidelity due to a characterisa-

tion error of the coupling of the control to the qubit. We analyse the control landscape obtained by

optimal control and find it to be dependent on the error and that the optimisation is less likely to

converge at a slow gate-time. Robust controls are found for different error rates and are compared

to incoherent loss of fidelity mechanism due to a finite relaxation rate. The controls are tested on

the IBMQ’s qubit and found to demonstrate resilience against significant ∼ 10% errors.