No Arabic abstract
It is well known that in a two-slit interference experiment, if the information, on which of the two paths the particle followed, is stored in a quantum path detector, the interference is destroyed. However, in a setup where this path information is erased, the interference can reappear. Such a setup is known as a quantum eraser. A generalization of quantum eraser to a three-slit interference is theoretically analyzed. It is shown that three complementary interference patterns can arise out of the quantum erasing process.
The issue of interference and which-way information is addressed in the context of 3-slit interference experiments. A new path distinguishability ${mathcal D_Q}$ is introduced, based on Unambiguous Quantum State Discrimination (UQSD). An inequality connecting the interference visibility and path distinguishability, ${mathcal V} + {2{mathcal D_Q}over 3- {mathcal D_Q}} le 1$, is derived which puts a bound on how much fringe visibility and which-way information can be simultaneously obtained. It is argued that this bound is tight. For 2-slit interference, we derive a new duality relation which reduces to Englerts duality relation and Greenberger-Yasins duality relation, in different limits.
A three-slit ghost interference experiment with entangled photons is theoretically analyzed using wave-packet dynamics. A non-local duality relation is derived which connects the path distinguishability of one photon to the interference visibility of the other.
The validity of the superposition principle and of Borns rule are well-accepted tenants of quantum mechanics. Surprisingly, it has recently been predicted that the intensity pattern formed in a three-slit experiment is seemingly in contradiction with the predictions of the most conventional form of the superposition principle when exotic looped trajectories are taken into account. However, the probability of observing such paths is typically very small and thus rendering them extremely difficult to measure. In this work, we confirm the validity of Borns rule and present the first experimental observation of these exotic trajectories as additional paths for the light by directly measuring their contribution to the formation of optical interference fringes. We accomplish this by enhancing the electromagnetic near-fields in the vicinity of the slits through the excitation of surface plasmons. This process effectively increases the probability of occurrence of these exotic trajectories, demonstrating that they are related to the near-field component of the photons wavefunction.
We study the dynamical entanglement distribution in a multipartite system. The initial state is a maximally entangled two level atom with a single photon field. Next a sequence of atoms are sent, one at the time, and interact with the field. We show that the which way information initially stored only in the field is now distributed among the parties of the global system. We obtain the corresponding complementarity relations in analytical form. We show that this dynamics may lead to a quantum eraser phenomenon provided that measurements of the probe atoms are performed in a basis which maximizes the visibility. The process may be realized in microwave cavities with present technology.
The measurable degree of entanglement from a quantum dot via the biexciton-exciton cascade depends crucially on the bright exciton fine-structure splitting and on the detection time resolution. Here, we propose an optical approach with fast rotating waveplates to erase this fine-structure splitting and therefore obtain a high degree of entanglement with near-unity efficiency. Our optical approach is possible with current technology and is also compatible with any quantum dot showing fine-structure splitting.