Strong quantum scarring by local impurities

TL;DR

This paper uncovers strong quantum scars in 2D quantum wells with local impurities, driven by classical resonances and quantum near-degeneracy, enabling efficient quantum transport and wave-packet control.

Contribution

It reveals a new type of quantum scars supported by classical resonances, distinct from traditional scar theory, and demonstrates their potential for quantum transport.

Findings

Quantum scars are supported by classical resonances and quantum near-degeneracy.

Preferred impurity orientations enhance quantum wave packet transport.

Wave-packet recurrences are stronger with scars than without.

Abstract

We discover and characterize strong quantum scars, or eigenstates resembling classical periodic orbits, in two-dimensional quantum wells perturbed by local impurities. These scars are not explained by ordinary scar theory, which would require the existence of short, moderately unstable periodic orbits in the perturbed system. Instead, they are supported by classical resonances in the unperturbed system and the resulting quantum near-degeneracy. Even in the case of a large number of randomly scattered impurities, the scars prefer distinct orientations that extremize the overlap with the impurities. We demonstrate that these preferred orientations can be used for highly efficient transport of quantum wave packets across the perturbed potential landscape. Assisted by the scars, wave-packet recurrences are significantly stronger than in the unperturbed system. Together with the controllability of the preferred orientations, this property may be very useful for quantum transport applications.