# Dark state with counter-rotating dissipative channels

**Authors:** Zheng-yang Zhou, Mi Chen, Lian-Ao Wu, Ting Yu, J. Q. You  
**arXiv:** [1703.10775](https://arxiv.org/abs/1703.10775)  
**Date:** 2017-03-31  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/1703.10775v2/

## Key points

- The concept of a dark state is crucial in chip-scale atomic clocks and quantum information
- Previous studies have neglected counter-rotating terms in the system-environment interaction
- Zheng-yang Zhou et al. studied non-Markovian quantum dynamics of the dark state in a $\Lambda$-type three-level system coupled to two bosonic baths
- Counter-rotating terms were found to cause leakage of the dark state even at zero temperature, contrary to previous assumptions
- A method was presented to restore quantum coherence to the dark state by applying a leakage elimination operator to the system
- This study highlights the importance of considering counter-rotating terms when studying dark states in $\Lambda$-type three-level systems and provides insight into how they can be controlled for practical applications.

## Summary

In the field of chip-scale atomic clocks and quantum information, the concept of a dark state - a superposition of two lowest states without dipole transition between them - is crucial. Previous studies have been based on the rotating-wave approximation (RWA), which neglects counter-rotating terms in the system-environment interaction. Zheng-yang Zhou et al. studied non-Markovian quantum dynamics of the dark state in a $\Lambda$-type three-level system coupled to two bosonic baths and revealed the effect of counter-rotating terms on the dark state. Contrary to previous assumptions, leakage of the dark state occurs even at zero temperature due to these counter-rotating terms. The authors presented a method to restore quantum coherence to the dark state by applying a leakage elimination operator to the system. This study highlights how important it is to consider counter-rotating terms when studying dark states in $\Lambda$-type three-level systems and provides insight into how they can be controlled for practical applications.