Study on the decoherence rate due to laser frequency fluctuation in Λ- type electromagnetically induced transparency

Ko-Tang Chen^1*, Bongjune Kim¹, Chia-Yu Hsu¹, Shih-Si Hsiao¹, Ite A. Yu^1,2

¹Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
²Center for Quantum Technology, Hsinchu 30013, Taiwan

* Presenter:Ko-Tang Chen, email:asd6939937510@gmail.com

Two-photon electromagnetically induced transparency (EIT) transition involving a Rydberg state can transfer ground-state atoms to Rydberg-state atoms, which induce strong dipole-dipole interaction and significantly enhance photon-photon interactions. Therefore, Rydberg-EIT system is very useful in quantum information science. However, the frequency stabilization method such as the injection-lock scheme cannot be applied to two laser fields with rather different wavelengths in the Rydberg-EIT system. The effect on of laser frequency fluctuation on the decoherence rate cannot be ignored.

In this presentation, the analytical formula we derived to predict the decoherence rate induced by laser frequency fluctuations will be reported. To test our analytical formula, we employed the Λ-type EIT system in the study, because the actual frequency fluctuations and laser linewidths of the probe and coupling fields can be eliminated by the injection-lock method. On the other hand, we can controllably introduce the artificial laser frequency fluctuation by applying the external frequency noise. The result shows that the predictions of our analytical formula are in good agreement with the experimental data.

Keywords: Rydberg atom, electromagnetically induced transparency