Sensitivity and robustness of quantum spin1 rings to parameter uncertainty Selective transfer of information between spin12 particles arranged in a ring is achieved by optimizing the transfer fidelity over a readout time window via shaping, externally applied, static bias fields. Such static control fields have properties that clash with the expectations of classical control theory. Previous work has shown that there are cases in which the logarithmic differential sensitivity of the transfer fidelity to uncertainty in coupling strength or spillage of the bias field to adjacent spins is minimized by controllers that produce the best fidelity. Here we expand upon these examples and examine cases of both classical and nonclassical behavior of logarithmic sensitivity to parameter uncertainty and robustness as measured by the p function for quantum systems. In particular we examine these properties in an 11spin ring with a single uncertainty in coupling strength or a single bias spillage.

Optimal controls of invariantbased population transfer in a superconducting qutrit Optimization of the control operations is of critical importance in the context of quantum information processing. We adopt optimal control techniques to implement invariantbased quantum population transfer in a superconducting qutrit. The first three levels of a chargephase quantum circuit constitute an effective qutrit. By applying two microwave drivings, a Lambda configuration interaction appears in the qutrit. The population transfers can be performed using the invariantbased shortcuts. Particularly, taking the methods of optimal control in resonant and nonresonant cases, we implement the accelerated transfer operation in which the noise effects can be reduced greatly, and realize the high transfer insensitivity to deviation error of Rabi coupling, respectively. Our strategy could offer a promising approach to investigate robust state transfer with superconducting artificial atoms experimentally.