 The paper proposes a differential detection scheme based on coexisting electromagnetically induced transparency, EIT, and absorption, EIA. Signals in a double system with counter-propagating bichromatic laser fields, which enhances the amplitude of the coherent population trapping, different CPT. The signal was suppressing common-mode noise, resulting in an improved signal-to-noise ratio for captain clocks, and potentially benefiting other applications, such as magnetometers, and precision spectroscopy. This article was offered by Ching Lin Lee, Peter Yoon, Tan Hoi Yan, and others.