Quantum detection of microwave and terahertz signals using Rydberg EIT/EIA spectroscopy

Introduction: Quantum light–matter interaction provides an excellent application of Rydberg levels. Rydberg states are special in the sense that they have a long lifetime and large dipole moments. The large number of these levels and the spacing among them enable the detection of the incoming signals in the broad region of the electromagnetic spectrum, encompassing microwave (MW), terahertz (THz) and radio frequency (RF) ranges. Electromagnetically Induced Absorption (EIA) and Transparency (EIT) can be achieved at these levels. MW and THz signals can quantum-mechanically split the relevant spectral lines in which the splitting is proportional to the strength of an incoming em field.