Bell's inequality for the Mach-Zehnder interferometer

Kicheon Kang, Kahng Ho Lee

Yunjin Choi, Justin Dressel, Andrew N. Jordan

Chithrabhanu Perumangatt, Tang Sheng, Alexander Ling

Entanglement distillation is the process of concentrating entanglement from a given quantum state. We present a technique for distillation of bipartite polarization entanglement using interferometry. This technique can be optimized to extract maximal entanglement from any pure or mixed entangled state. A model for this method is presented, and, in particular, we present experimental results for pure states when using polarizing Mach-Zehnder interferometers. These experimentally distilled states always demonstrate an increased violation of Bell's inequality.

Adam Powell

As part of developing a Bell’s Inequality Test of Quantum Mechanics laboratory at CWU we have investigated classical interference using a Fabry-Perot and a Mach-Zehnder interferometer. The classical interference investigation was done using several HeNe lasers of different wavelengths. Optimization of data collection for the classical systems was accomplished by fabricating several pieces: a motorized micrometer platform, building a mount for a piezo electric tube, and building a fringe counting circuit. To investigate quantum interference the same Mach-Zhender interferometer was used but the HeNe laser beam was attenuated. We investigated alternative methods for attenuating the HeNe laser beam. An SBIG ST-7 CCD camera was evaluated for use as a single photon detector and used to collect data from the Mach-Zehnder interferometer. The results were compared with results using a single photon counting module. The results were consistent with the predictions of single photon interference in the Mach-Zehnder interferometer.

Marek Żukowski

A. A. Vishnevyy, Gordey B. Lesovik

The parameters at which the maximally entangled two-particle state appears in the system of two ideal electronic Mach-Zehnder interferometers are known. In this work, the operation of nonideal devices with finite scattering in splitters and with reflection in the region of the Coulomb Interaction has been considered. It has been shown that, under the condition of postselection of experimental results, these factors can increase the observed Bell parameter to values exceeding Cirel’son’s (or Tsirelson’s) bound equal to 2√2 up to the mathematical limit equal to 4. A simple postselective measurement scheme providing B = 4 has been described. Although the results of such measurements are not as fundamental as the observation of the violation of Bell’s inequality, they can indirectly indicate the existence of an entangled state in the system. The measurement system is more stable against fluctuations of the phase than a system without postselection. Furthermore, it has been found that the proposed system is optimal for investigation of cross correlations between interferometers in the dc regime (beyond the paradigm of the violation of Bell’s inequality) because they cannot be generated by coordinated fluctuations of Aharonov-Bohm phases.