Double dark resonances and the dispersion properties in a four-level inverted-Y atomic system

The electromagnetically induced transparency (EIT) and its dispersion properties in a four-level inverted-Y atomic system are investigated. The absorption spectrum of a weak probe field shows two EIT windows (dark resonances) whose location, width, and depth can be controlled by manipulating the parameters of the coupling fields; the corresponding dispersion properties are also measured by using a Mach–Zehnder interferometer. The experimental measurements agree well with the theoretical calculations. This kind of system can find important applications in two-channel quantum communication and information storage.

Research Highlights
► Experimental observation of the double dark resonance and its dispersion properties in an inverted Y system in Rb vapor.
► Enhancement of electromagnetically induced transparency dip and corresponding dispersion.
► Slow light in two EIT channels.