Nonadiabatic control of quantum transport fidelity in dissipative cold media

Abstract

We put forth a hitherto unexplored control strategy that enables finite-speed, high-fidelity transport of a quantum wavepacket through a low-temperature dissipative medium. The control consists in confining the wavepacket within a shallow anharmonic trap (tweezer), whose nonuniform velocity is steered so as to maximize the transfer fidelity between two locations. A relevant scenario is a quantum impurity moving through an ultracold gas. Unlike shortcuts to adiabaticity, our approach can simultaneously cope with wavepacket leakage via non-adiabatic and phonon-mediated processes, provided both act perturbatively. Nor does our approach require the application of compensating forces or counter-diabatic fields and thereby avoids the practical shortcomings of shortcut techniques. Instead, optimal (highest fidelity) transport is achieved here by minimizing the functional overlap of the varying velocity-spectrum of the chosen trajectory with the combined (bath-induced and non-adiabatic) leakage spectrum.