Abstract
We study quasibound states and scattering with short-range potentials in three dimensions, subject to an axial periodic driving. We find that poles of the scattering matrix can cross the real energy axis as a function of the drive amplitude, making the matrix nonanalytic at a singular point. For the corresponding quasibound states that can tunnel out of (or get captured within) a potential well, this results in a discontinuous jump in both the angular momentum and energy of emitted (absorbed) waves. We also analyze elastic and inelastic scattering of slow particles in the time-dependent potential. For a drive amplitude at the singular point, there is a total absorption of incoming low-energy ( wave) particles and their conversion to high-energy outgoing (mostly ) waves. We examine the relation of such Floquet singularities, lacking in an effective time-independent approximation, with well-known “spectral singularities” (or “exceptional points”). These results are based on an analytic approach for obtaining eigensolutions of time-dependent periodic Hamiltonians with mixed cylindrical and spherical symmetry, and apply broadly to particles interacting via power-law forces and subject to periodic fields, e.g., co-trapped ions and atoms.
8 More- Received 4 September 2017
- Revised 12 February 2018
DOI:https://doi.org/10.1103/PhysRevA.97.042705
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