Simulation of Electromagnetically Induced Transparency and Autler-Townes Splitting in Microwave Frequency Range

The paper shows the possibility of modelling the Autler-Townes splitting (ATS) effect using resonant elements in the microwave range. The spectrum of oscillations of a low-pass filter on two microstrip resonators, the lengths of which differ by a factor of two, was studied. In the frequency range where the second harmonic of the short resonator and the fourth harmonic of the long resonator are close in frequency, an oscillation occurs that is in good agreement with ATS-type splitting. It was established that to achieve a pronounced "failure" of the attenuation characteristic of such a rejection filter ("transparency window"), the Q-factor of the resonators must differ significantly. Notable features of ATS are shown, including a deep "window of transparency" for the same types of oscillations with similar Q-factors and the presence of negative group delay times in the splitting region.

I. Introduction

Electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) are two phenomena that involve coherent interactions of light with multilevel systems. EIT enables various quantum applications, such as non-linear optics, information storage and processing, repeaters, and atomic cooling [1], [2]. ATS has potential applications for efficient broadband quantum memory and processing devices [3]. EIT and ATS can also potentially be used to measure the strength of a continuous-wave radio-frequency electric field based on Rydberg atoms in an atom pair [4]. EIT is a quantum interference effect that creates a narrow transparency window in the absorption spectrum of a medium, while ATS is a field-induced splitting of energy levels that also results in a transparency window [5]. Both EIT and ATS have potential applications in nonlinear optics, quantum information, and slow light. However, distinguishing between EIT and ATS is not trivial, as they both produce similar spectral features [6]. Moreover, various analogues of EIT and ATS can be realized in different physical systems, such as plasmonics, metamaterials, optomechanics, and coupled resonators [7].