Difference between revisions of "Main Page/PHYS 4210/Bell's Inequalities"

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<li>Coincidence</li>
 
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Revision as of 14:41, 28 January 2014

Bell's Inequalities and Quantum Entanglement

Deep at the root of the underlying principles of quantum mechanics lies shadowy principles based on probability which never sit well with some people. This experiment is meant to shine some (laser)light on these principles, and see if we can't come to some deeper understanding of the underlying framework of Quantum Dynamics.

No better introduction can be given than the following set of famous papers, commonly referred to today by their author lists.

  • Einstein, Podolsky, Rosen[1]
  • Bell[2]
  • CHSH (Clauser, Horne, Shimony, & Holt)[3]

It is imperative that you read and understand these papers before you attempt to perform this experiment.

Another useful resource, more directly relevant to the experiment you will be performing is from Dehlinger and Mitchell [4].

Key Concepts

  • Entanglement
  • Parametric down conversion
  • Nonlocality
  • Coincidence
  • Correlation
  • Logic Analyzer
  • Avalanche Photodiode

Method



Core Experiment

To setup the experiment as described in the methods sections and to take one complete set of data required to test Bell's Inequality as described in [4] using the readings from the ratemeter. A full analysis of the data with proper treatment of uncertainties is required.


You are required to complete the core experiment along with your choice of one of the modules listed below.

Module 1: Purity of Correlation

In this module, you will try to improve on the purity of the correlation by reducing the acceptance angle of the single-photon detectors by place adjustable collimating slits into each path before the single photon detectors.

Module 2: Computer Analysis

In this module, you will use a Logic Analyzer to collect the raw outputs from the individual single photon detectors, then create an analysis program to calculate coincidence. Once this is accomplished, you can take data for longer periods of time and reduce the statistical uncertainties.

Module 3: Pump Laser Power

In this module, you will vary the power of the 405nm pump laser beam using neutral density filters in order to study the rate of coincident photon as a function of pump laser power. Does this trend follow expectations?



References

  1. A. Einstein, B. Podolsky & N. Rosen, "Can Quantum-Mechanical Description of Physical Reality Be Considered Complete?" Phys. Rev., 47, 777-780 (1935)
  2. J.S. Bell, "On the Einstein Podolsky Rosen Paradox" Physics, 1, 195 (1964)
  3. J.F. Clauser, M.A. Horne, A. Shimony, & R.A. Holt, "Proposed Experiment to Test Local Hidden-Variable Theories" Phys. Rev. Lett., 23, 880 (1969)
  4. 4.0 4.1 D. Dehlinger & M.W. Mitchell "Entangled photons, nonlocality and Bell inequalities in the undergraduate laboratory." Am. J. Phys. 70, 903 (2002)