Young’s Double-Slit and Wheeler’s Delayed-Choice Experiments: What’s Really Happening at the Single-Quantum Level? N. Gurappa ∗ Research Center of Physics, Vel Tech Multitech Dr.Rangarajan Dr.Sakunthala Engineering College, Avadi, Chennai, Tamil Nadu 600 062, India A new ‘wave-particle non-dualistic interpretation’ at the single-quantum level, existing within the quantum formalism, is presented by showing the Schr¨ odinger wave function as an ‘instantaneous resonant spatial mode’ where a particle moves. For the first time, the position eigenstate of a particle is identified to be related to the absolute phase of the wave function in such a way that its position eigen values always lie on a classical trajectory, proving that the ‘time parameter’ is common to both classical and quantum mechanics. It’s brought into light that the quantum formalism demands a different kind of boundary conditions to be imposed to the wave function unlike classical formalism and hence naturally yields the Born rule as a limiting case of the relative frequency of detection. This derivation of the Born rule automatically resolves the measurement problem. Also, these boundary conditions immediately expound Bohr’s principle of complementarity at a single quantum level. Further, the non-duality naturally contains the required physical mechanism to elucidate why the Copenhagen interpretation is experimentally so successful. The single-quantum phenomenon is then used to unambiguously explain what’s really going on in the Young double-slit experiment as anticipated by Feynmann and the same is again used to provide a causal explanation of Wheeler’s delayed-choice experiment. PACS numbers: 03.65 Ta, 03.65 -w, 03.65 Ca, 03.65 Yz, 03.67 -a, 03.75 -b I. INTRODUCTION For nearly hundred years, there is no consensus about what kind of physical reality is being revealed by the quantum formalism irrespective of its ability to accu- rately predict the outcomes of innumerable experiments. It’s an extremely successful theoretical description of Na- ture, especially in the atomic scale, where the classical mechanistic concepts seem to fail completely. Therefore, the exact interpretation of the quantum formalism is very important as it can naturally yield an intuitive visualiza- tion of the true picture of reality which will surely con- tribute to the deeper developments in the fundamental physics. Its one immediate application will be in quan- tum computers. Consider Young’s double-slit (YDS) experiment [1] with a single-quantum source (Fig. 1). Every quantum is fired at the YDS one-at-a-time. The time interval be- tween any two consecutively fired quanta is chosen to be greater than the time of arrival of one quantum from the source to the screen. This choice guarantees that every quantum is independent of every other one and hence the behavior of an individual quantum becomes transparent. As a large number of quanta are being collected on the screen, an interference pattern, reminiscent of wave na- ture, gradually emerges out. If slit-1 (slit-2) is blocked, then a clump pattern corresponding to single-slit diffrac- tion of slit-2 (slit-1), supposed to be of particle nature, occurs on the same screen. This implies that every indi- vidual quantum is aware of how many slits are opened. * ngurappa@veltechmultitech.org Figure 1. Single-quantum Young’s double-slit exper- iment: A source shoots quanta, one at a time, towards a double-slit assembly. 1 and 2 represent two slits through which the state vectors |S1 > and |S2 > get excited and su- perposed as |S>= |S1 > +|S2 >. B1 and B2 are two blockers which can block either slit-1 or slit-2 at any time. D1 and D2 are two detectors useful to find out through which slit any quantum is passing towards the screen. Immediately behind the screen, a twin-telescopes, T1 and T2, is placed such that the quanta passing through slit-1 and slit-2 reach T1 and T2, respectively. After collecting a large number of quanta, the re- sulting distribution patterns at the screen and the telescopes were given at the right hand side. If both slits are opened, then the observed distribution is <S|S>. If slit-2 (slit-1) is blocked, then the distribution is <S1|S1 > (<S2|S2 >). The observed interference pattern suggests to infer that the quantum ‘somehow’ simultaneously passes through both the slits like a wave. However, this inference fails during the experimental observation, because, a quan- tum always appears going through either slit-1 or slit-2 like a particle but never simultaneously through both the