Two-level system in a sinusoidal electric field

Namita Gupta

J.V. Moloney, M. K. Ali, William J. Meath

A. Muriel

Shekhar Guha, Martin A. Gundersen

Stefano Longhi

It is theoretically shown that the tunnelling dynamics of light between two sinusoidally curved coupled optical waveguides of different sizes exactly mimics the population dynamics of a two-level system with nonzero diagonal dipole matrix elements subjected to an applied sinusoidal electric field, thus realizing an optical analogue of a two-level dipolar molecule in an external ac field. Some characteristic dynamical features, including multi-photon transitions, sinusoidal population oscillations built up in a series of stair steps or square-wave population oscillations, are reproduced in the optical waveguide system. Design parameters for their observation are given with reference to lithium-niobate optical waveguides.

William J. Meath, Edwin Albert Power

Solutions of the time-dependent Schrödinger equation, in the semi-classical electric dipole approximation, are developed for the interaction of a two-level system, possessing both transition and diagonal dipole matrix elements, with applied static and sinusoidal electric fields. Exact solutions can only be obtained subject to conditions involving the orientations and strengths of the applied fields. These, and perturbative extensions, are used to discuss some of the features of multi-photon processes that depend on the existence of non-zero diagonal dipole matrix elements. Some of the results apply, in the limit of vanishing permanent moments, to the atomic two-level problem.