scholarly journals Reality or Locality? Proposed Test to Decide How Nature Breaks Bell's Inequality

2012 ◽  
Vol 2012 ◽  
pp. 1-5
Author(s):  
Johan Hansson

Bell's theorem, and its experimental tests, has shown that the two premises for Bell's inequality—locality and objective reality—cannot both hold in nature, as Bell's inequality is broken. A simple test is proposed, which for the first time may decide which alternative nature actually prefers on the fundamental, quantum level. If each microscopic event is truly random (e.g., as assumed in orthodox quantum mechanics) objective reality is not valid whereas if each event is described by an unknown but deterministic mechanism (“hidden variables”) locality is not valid. This may be analyzed and decided by the well-known reconstruction method of Ruelle and Takens; in the former case no structure should be discerned, in the latter a reconstructed structure should be visible. This could in principle be tested by comparing individual “hits” in a double-slit experiment, but in practice a single fluorescent atom, and its (seemingly random) temporal switching between active/inactive states would possibly be better/more practical, easier to set up, observe, and analyze. However, only imagination limits the list of possible experimental setups.

2001 ◽  
Vol 1 (Special) ◽  
pp. 113-123
Author(s):  
D. Kielpinski ◽  
A. Ben-Kish ◽  
J. Britton ◽  
V. Meyer ◽  
M.A. Rowe ◽  
...  

We review recent experiments on entanglement, Bell's inequality, and decoherence-free subspaces in a quantum register of trapped {9Be+} ions. We have demonstrated entanglement of up to four ions using the technique of Molmer and Sorensen. This method produces the state ({|\uparrow\uparrow\rangle}+{|\downarrow\downarrow\rangle})/\sqrt{2} for two ions and the state ({\downarrow}{\downarrow}{\downarrow}{\downarrow} \rangle + | {\uparrow}{\uparrow}{\uparrow}{\uparrow} \rangle)/\sqrt{2} for four ions. We generate the entanglement deterministically in each shot of the experiment. Measurements on the two-ion entangled state violates Bell's inequality at the 8\sigma level. Because of the high detector efficiency of our apparatus, this experiment closes the detector loophole for Bell's inequality measurements for the first time. This measurement is also the first violation of Bell's inequality by massive particles that does not implicitly assume results from quantum mechanics. Finally, we have demonstrated reversible encoding of an arbitrary qubit, originally contained in one ion, into a decoherence-free subspace (DFS) of two ions. The DFS-encoded qubit resists applied collective dephasing noise and retains coherence under ambient conditions 3.6 times longer than does an unencoded qubit. The encoding method, which uses single-ion gates and the two-ion entangling gate, demonstrates all the elements required for two-qubit universal quantum logic.


1994 ◽  
Vol 29 (1) ◽  
pp. 63-105
Author(s):  
Kaj Børge Hansen

Eight derivations of Bell’s inequality are given. First a simple and concrete derivation is given drawing on the full strength of the two hypotheses of locality and hidden variables. Two attempts at deriving Bell’s inequality without locality are made. They fail, but give valuable insight into the form which nonlocality must take in quantum physics. Arguments are given against this form of nonlocality. Ontological ideas which allow separation, realism, and locality in quantum mechanics (QM) are indicated. In the following five derivations, a number of variants of the assumption of hidden variables are tried. Among the insights which these derivations give rise to are: (1) Particles cannot be assumed to have spin or polarisation values for as much as one fixed direction. (2) The classical picture of electromagnetic radiation is incompatible with QM. (3) Heisenberg’s idea of potentiality in elementary particles is incompatible with QM. (4) There is a weakest form of hidden variables, called realisability, which is sufficient to yield Bell’s inequality. (5) Quantum states cannot be identified with physical states. The mathematical problem of the integration of quantum states into physical states is nontrivial.


Author(s):  
M. Suhail Zubairy

The first round of the Einstein–Bohr debates took place when Einstein challenged Bohr’s principle of complementarity at the Solvay conference in 1927 and Bohr successfully defended it. The most serious challenge, however, came in 1935 when a paper by Einstein, Podolsky, and Rosen (EPR) argued that quantum mechanics was incomplete through a gedanken experiment motivating an approach based on hidden variables. In this chapter, EPR’s arguments about the incompleteness of quantum mechanics and Bohr’s reply to them are presented. The ultimate answer came almost 30 years later, almost ten years after Einstein’s death, and was nothing that Einstein would have expected. Bell’s inequality and the subsequent Bell-CHSH inequality, that are satisfied by all theories based on the “self-evident truths” of reality and locality are discussed. The startling results that quantum mechanics violates Bell’s inequality and the experimental results are in agreement with the prediction of quantum mechanics are presented.


2015 ◽  
Vol 154 ◽  
pp. 49-56 ◽  
Author(s):  
Stefano Frabboni ◽  
Gian Carlo Gazzadi ◽  
Vincenzo Grillo ◽  
Giulio Pozzi

2010 ◽  
Vol 09 (04) ◽  
pp. 423-426 ◽  
Author(s):  
DAVID K. FERRY ◽  
LASZLO B. KISH

To many, the idea of the EPR paradox and the possibility of local hidden variables were dismissed by the Bell inequality, although the central points of this argument have been around since the advent of quantum mechanics. Yet, there remains considerable evidence that this inequality can be violated even by classical systems. The question really is whether or not strongly correlated classical fields will also violate Bell's inequality. In a previous paper, it was shown that this was the case. Here, we ask the question as to just how much correlation in the classical waves is required to violate the inequality.


2015 ◽  
Vol 9 (3) ◽  
pp. 2470-2475
Author(s):  
Bheku Khumalo

This paper seeks to discuss why information theory is so important. What is information, knowledge is interaction of human mind and information, but there is a difference between information theory and knowledge theory. Look into information and particle theory and see how information must have its roots in particle theory. This leads to the concept of spatial dimensions, information density, complexity, particle density, can there be particle complexity, and re-looking at the double slit experiment and quantum tunneling. Information functions/ relations are discussed.


2015 ◽  
Vol 10 (2) ◽  
pp. 2692-2695
Author(s):  
Bhekuzulu Khumalo

Heat has often been described as part of the energy transfer process. Information theory says everything is information. If everything is information then what type of information is heat, this question can be settled by the double slit experiment, but we must know what we are looking for. 


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