Strengthen Weak Measurement with Conjugated Destructive Interference
  Standard weak measurement (SWM) has been proved to be a useful ingredient for measuring small longitudinal phase shifts. [Phys. Rev. Lett. 111, 033604 (2013)]. In this letter, we show that with specfic pre-coupling and postselection, destructive interference can be observed for the two conjugated variables, i.e. time and frequency, of the meter state. Using a broad band source, this conjugated destructive interference (CDI) can be observed in a regime approximately 1 attosecond, while the related spectral shift reaches hundreds of THz. This extreme sensitivity can be used to detect tiny longitudinal phase perturbation. Combined with a frequency-domain analysis, conjugated destructive interference weak measurement (CDIWM) is proved to outperform SWM by two orders of magnitude. 
Zi-Huai Zhang, Geng Chen, Xiao-Ye Xu, Jian-Shun Tang, Wen-Hao Zhang,   Yong-Jian Han, Chuan-Feng Li, Guang-Can Guo
quant-ph