Weak Measurement Based On Joint-measurement

Weak measurement is one of the most promising research tools in quantum mechanics.In the weak measurement,the weak-value amplification can be used to measure the tiny physical effects.In the measurement process,the tiny physical effects can be amplified.However,the price to be paid for this amplification is due to the reason of the post-selection.Loss of data,that is,only a small portion of the light that the detector can receive,the measured light intensity is relatively low and may exceed the detector's measurement threshold.This is the limitation of weak measurement.How to overcome this limitation is the next problem to be solved.Strong post-selection is necessary for anomalous amplification in WVA techniques,but discarding data counts has been the target of criticism,and even considered" harmful"for metrology.This article is about a method that can both amplify the amount to be measured without discarding the data,that is,almost-balanced weak values technology.The basis of this technique is to jointly measure weak interactions and away from weak values to zoom in approximations.Two detectors are used to collect complete statistics of the correlation between the two weakly entangled degrees of freedom.Without discarding the data,this method is similar to the anomalous amplification of weak values.The amplification is introduced in the differential signal of the two detectors,making it robust to different sources of technical noise,and also provides the advantage of a balanced signal for precision measurement.This method does not require the post-selection part of the weak amplification technique,and the data lost through abnormal amplification is also recovered.The small phase that controls the unbalance of the differential signal also plays a similar role in the post-selection of the weak value amplification.