Quantum interference as phase space filtering

C. M. A. Dantasox, B. Baseia

Yinghong Xue

Daniela Dragoman

A phase-space formulation of the filtering process of a quantum state is developed that models both quantum interference and delayed-choice experiments without reference to the controversial wave-particle duality concept and without any explicit model of the interaction between the particles and the measuring apparatus. Quantum particles are considered as localized and indivisible concentrations of energy and/or mass, their probability amplitude in phase space being described by the Wigner distribution function. The "wave" or "particle" nature emerges in experiments in which the interference term of the Wigner distribution function is present or absent, respectively. The Wigner distribution function is modified by filtering devices that act on the quantum wave function throughout the setup, from its generation to its final detection.

Wiktor Szadowiak, Sanjukta Kundu, Jerzy Szuniewicz +1 more

Quantitative characterization of the spatial structure of single photons is essential for free-space quantum communication and quantum imaging. We introduce an interferometric technique that enables the complete characterization of a two-dimensional probability amplitude of a single photon. Importantly, in contrast to methods that use a reference photon for the phase measurement, our technique relies on a single photon interfering with itself. Our setup comprises of a heralded single-photon source with an unknown spatial phase and a modified Mach-Zehnder interferometer with a spatial filter in one of its arms. The spatial filter removes the unknown spatial phase and the filtered beam interferes with the unaltered beam passing through the other arm of the interferometer. We experimentally confirm the feasibility of our technique by reconstructing the spatial phase of heralded single photons using the lowest order interference fringes. This technique can be applied to the characterization of arbitrary pure spatial states of single photons.

М. А. Захаров, Aleksandr I Frank, G. V. Kulin +1 more

Abstract The problem of the interaction of ultracold neutrons with a neutron interference filter oscillating in space is investigated. In the problem, the evolution of the wave packet is considered by means of numerically solving the non-stationary Schrödinger equation by splitting the evolution operator. The filter oscillating in space acts as a quantum modulator of the ultracold neutron flux. The resulting spectra of the transmitted and reflected states are obtained depending on the motion parameters of the interferometer.