An Ideal Experiment to Determine the 'Past of a Particle' in the Nested Mach–Zehnder Interferometer
LI Fu1**, Hashmi F. A.2, ZHANG Jun-Xiang3, ZHU Shi-Yao1,3,4
1Beijing Computational Science Research Center, Beijing 100094 2Department of Physics, COMSATS Institute of Information Technology, Islamabad, Pakistan 3The State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan 030006 4Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei 230026
Abstract：An ideal experiment is designed to determine the past of a particle in the nested Mach–Zehnder interferometer (MZI) by using standard quantum mechanics with quantum non-demolition measurements. We find that when the photon reaches the detector, it only follows one arm of the outer interferometer and leaves no trace in the inner MZI. When it goes through the inner MZI, it cannot reach the detector. Our result obtained from the standard quantum mechanics contradicts the statement based on two-state vector formulism, 'the photon did not enter the (inner) interferometer, the photon never left the interferometer, but it was there'. Therefore, the statement and also the overlapping claim are incorrect.
. [J]. 中国物理快报, 2015, 32(5): 50303-050303.
LI Fu, Hashmi F. A., ZHANG Jun-Xiang, ZHU Shi-Yao. An Ideal Experiment to Determine the 'Past of a Particle' in the Nested Mach–Zehnder Interferometer. Chin. Phys. Lett., 2015, 32(5): 50303-050303.
2015, Vol. 32 
