Acceleration of trapped particles and beams

TL;DR

This paper investigates the quantum dynamics of particles trapped by an accelerating delta potential, analyzing stationary, pulling, and pushing scenarios, with analytical approximations and potential optical analogs.

Contribution

It introduces a detailed analysis of particle behavior under accelerating delta potentials, including new analytical approximations for different regimes and potential optical applications.

Findings

Trapped particle lifetime and maximum acceleration velocity are determined.

Analytical solutions are developed for small and large accelerations.

The regimes can be realized in optical beams guided by bending potential channels.

Abstract

The dynamics of a quantum particle bound by an accelerating delta-functional potential is investigated. Three cases are considered, using the reference frame moving along with the {\delta}-function, in which the acceleration is converted into the additional linear potential. (i) A stationary regime, which corresponds to a resonance state, with a minimum degree of delocalization, supported by the accelerating potential trap. (ii) A pulling scenario: an initially bound particle follows the accelerating delta-functional trap, within a finite time. (iii) The pushing scenario: the particle, which was initially localized to the right of the repulsive delta-function, is shoved to the right by the accelerating potential. For the two latter scenarios, the life time of the trapped particle, and the largest velocity to which it can be accelerated while staying trapped, are found. Analytical approximations are developed for the cases of small and large accelerations in the pulling regime, and also for a small acceleration in the stationary situation, and in the regime of pushing. The same regimes may be realized by Airy-like planar optical beams guided by a narrow bending potential channel or crest. Physical estimates are given for an atom steered by a stylus of a scanning tunneling microscope (STM), and for the optical beam guided by a bending stripe.