A single-photon source based on cavity quantum electrodynamics considering the re-excitation problem

Single photons play a crucial role in quantum information processing and have a multitude of applications, from quantum computation to quantum communication. While there are several physical implementations of single-photon sources, the cavity QED system is a physical system that can generate photons on demand. In single-photon generation by this system, the use of a Λ-type three-level atom allows control of the photon waveform. In this method, there is a process that inhibits ideal photon generation due to the relaxation of excited atoms to the initial state, which degrades the performance of quantum information processing utilizing photons. To address this issue, we propose a novel photon generation scheme using a four-level atom.

We demonstrate that the relaxation process described above can be made arbitrarily small by manipulating experimentally tunable parameters.