Demonstration of double EIT using coupled harmonic oscillators and RLC circuits

Single and double electromagnetically induced transparency (EIT) in a medium, consisting of fourlevel atoms in the inverted-Y configuration, are discussed using mechanical and electrical analogies. A three coupled spring-mass system subject to damping and driven by an external force is used to represent the four-level atom mechanically. The equations of motion of this system are solved analytically, which revealed single and double EIT. On the other hand, three coupled RLC circuits are used, as the electrical analog, to explore and experimentally demonstrate single and double EIT. The simplicity of these two models makes this experiment appropriate for undergraduate students and easy to incorporate into a college physics laboratory.