Quantum beats

In physics, quantum beats are simple examples of phenomena that cannot be described by semiclassical theory, but can be described by fully quantized calculation, especially quantum electrodynamics. In semiclassical theory (SCT), there is an interference or beat note term for both V-type and ${\displaystyle \Lambda }$-type atoms.^{[clarification needed]} However, in the quantum electrodynamic (QED) calculation, V-type atoms have a beat term but ${\displaystyle \Lambda }$-types do not. This is strong evidence in support of quantum electrodynamics.