Towards simultaneous observation of path and interference of a single photon in a modified Mach–Zehnder interferometer

Classical wisdom of wave-particle duality regulates that a quantum object shows either the particle or wave nature but never both.Consequently,it would be impossible to observe simultaneously the complete wave and particle nature of the quantum object.Mathematically the principle requests that the interference visibility V and whichpath distinguishability D satisfy an orthodox limit of V^2+D^2≤1.The present work reports a new waveparticle duality test experiment using single photons in a modified Mach-Zehnder interferometer to demonstrate the possibility of breaking the limit.The key element of the interferometer is a weakly scattering total internal reflection prism surface,which exhibits a pronounced single-photon interference with a visibility of up to 0.97and simultaneously provides a path distinguishability of 0.83.Apparently,the result of V^2+D^2≈1.63 exceeds the orthodox limit set by the classical principle of wave-particle duality for single photons.We expect that more delicate experiments in the future should be able to demonstrate the ultimate limit of V^2+D^2≈2 and shed new light on the foundations of con temporary quantum mechanics.