Speeding up quantum adiabatic processes with a dynamical quantum geometric tensor

Abstract

For adiabatic controls of quantum systems, the non-adiabatic transitions are reduced by increasing the operation time of processes. Perfect quantum adiabaticity usually requires the infinitely slow variation of control parameters. In this paper, we propose the dynamical quantum geometric tensor, as a metric in the control parameter space, to speed up quantum adiabatic processes and reach quantum adiabaticity in relatively short time. The optimal protocol to reach quantum adiabaticity is to vary the control parameter with a constant velocity along the geodesic path according to the metric. For the system initiated from the n-th eigenstate, the transition probability in the optimal protocol is bounded by P_{n}(t)\leq4\mathcal{L}_{n}^{2}/\tau^{2} with the operation time \tau and the quantum adiabatic length \mathcal{L}_{n} induced by the metric. Our optimization strategy is illustrated via two explicit models, the Landau-Zener model and the one-dimensional transverse Ising model.