Attosecond half-cycle light emission from a quantum well
Phys. Rev. A 113, 033516 – Published 12 March, 2026
DOI: https://doi.org/10.1103/ddm3-9b2h
Abstract
We introduce a fundamental mechanism for generating unipolar light at the atomic scale—nonrecollision unipolar emission—where tunneling ionization from a rectangular quantum well produces half-cycle attosecond pulses. Unlike all known microscopic strong-field processes in atoms (confirmed by our 1D and full 3D time-dependent Schrödinger equation simulations), which rely on recollision dynamics and yield oscillatory radiation, the flat potential of a rectangular quantum well suppresses electron return. This enables a clean ionization-stop sequence, resulting in unidirectional charge displacement and perfect unipolar waveforms. Numerical solutions of the time-dependent Schrödinger equation demonstrate that optimally shaped two-cycle laser pulses trigger this process, generating subfemtosecond unipolar pulses without secondary oscillations. This work establishes solid-state nanostructures as elementary quantum sources of unipolar radiation, solving the long-standing problem of identifying their fundamental origin and opening a research avenue for attosecond science and petahertz optoelectronics.
