Quantum entanglement

An even deeper dilemma confronts an honest physicist when trying to understand what really happens during a quantum measurement. Despite using (macroscopically) intuitive descriptions of the quantum-entangled objects, what really happens remains a deep mystery. Or, consider the following simple thought experiment using CA. 

A desire to understand quantum entanglement is fueled by the development of quantum computation, which started in the 1980s with the pioneering work of Benioff [26], Bennett [27], Deutsch [28], Feynman [29] and Landauer [30] but gathered momentum and research interest only after Peter Shor s revolutionary... 

Quantum entanglement between matter-sustained quantum states and those presenting EM quantum states is one basic ingredient in discussing, for example, Eq. (31) in Scully et al. atom interferometer analysis. Also, in Section 4.2, a quantized EM field was used. Some key issues were not examined there below focus is on one issue concerning laboratory (real)/Fock space [5] connection. 

To calculate the quantum potential it is first necessary to find R, which by equation 9 is clearly a function of all particle coordinates, because of nonlocal interaction in terms of the molecular quantum entanglement inferred before. Even when all particle coordinates and velocities (v = 0) are identical in the two states, the state S must therefore still be at a lower energy. The difference can only be attributed to the quantum potential which differs for the two states. The force that holds the molecule together is therefore seen to be a special case of non-local interaction within the molecule. 

A quantum computer thus has the capability of operating in a massively parallel mode. A 300-qubit quantum computer could theoretically store 2 10 bits of information, more than the estimated number of atoms in the known Universe, and also be capable of doing 2 ° simultaneous calculations. A classical computer can be likened to a solo musical instrument, a quantum computer to a full orchestra. If the music is well played, a symphony is much more profound than the sum of its parts. A major technical problem in constructing quantum computers is to minimize interactions within the machine and with the environment, which would cause decoherence—a breakdown in quantum entanglement. 

Bell s inequality provides a clear-cut test of local reality vs. quantum mechanics. The unambiguous answer, from a variety of experiments which we describe in the next section, is that quantum mechanics wins Thus, we can conclude that we live in a Universe which does not respect local reality. Quantum entanglement—a term introduced by Schrddinger—really happens In drawing this conclusion we are actually glossing over a number of still-unresolved hair-splitting metaphysical arguments. This remarkable result is often summarized as Bell s theorem ... 

This part is focussed on the intriguing question of quantum entanglement in large statistical condensed-matter ensembles and its possible influence on the cross-section of neutron scattering from solids ... 

Laboratoire Kastler Brossel is a laboratory of Universite Pierre et Marie Curie and ENS, associated to CNRS (UMR 8552). We acknowledge support of the European Community, of the Japan Science and Technology corporation (International Cooperative Research Project Quantum Entanglement). 

These NCS experiments [Chatzidimitriou-Dreismann 1997 (a) Chatzidimi-triou-Dreismann 1999 Karlsson 1999], which were motivated by the theoretical work of C. A. Chatzidimitriou-Dreismann [Chatzidimitriou-Dreismann 1991 Chatzidimitriou-Dreismann 1997 (b)] on protonic quantum entanglement in condensed systems and by the results of a an earlier Raman experiment on liquid H O / D O mixtures [Chatzidimitriou-Dreismann 1995], were followed by a series of other experiments on liquid and solid organic materials [Chatzidimitriou-Dreismann 2000 (b) Chatzidimitriou-Dreismann 2001 Chatzidimitriou-Dreismann 2002 (a)], various metallic hydrides [Abdul-Redah 2000 Karlsson 2002 (b) Karlsson 2003 (b)], liquid hydrogen [Chatzidimitriou-Dreismann 2004 (b)] and among others an ionic solid [Abdul-Redah 2004] using the same experimental technique, i.e., neutron Compton scattering. All these experiments confirmed the anomalous results found earlier and also revealed certain new aspects of the considered effect. 

As already mentioned above the experimental work on short-lived protonic quantum entanglement in condensed matter has been triggered by earlier theoretical and experimental work of C. A. Chatzidimitriou-Dreismann [Chatzidimitriou-Dreismann 1991 Chatzidimitriou-Dreismann 1997 (b)]. One model for the theoretical interpretation of the NCS results has been put forward by C. A. Chatzidimitriou-Dreismann et al. starting from the van Hove formalism for the scattering process and explicitly taking into account the irreversible dynamics of the decoherence process [Chatzidimitriou-Dreismann 2000 (b)]. This model has experienced a further development and extension [Chatzidimitriou-Dreismann 2003 (b)]. E. B. Karlsson and S. W. Lovesey have proposed another model [Karlsson 2002 (a)] relying on the existence of exchange cor-... 

In addition to the papers presenting the results of the various experimental techniques (e.g., NCS, ECS, elastic neutron scattering, IXS, etc.) applied to investigate protonic quantum entanglement in condensed matter, there are also papers in this part aiming at the theoretical interpretation of the experimental results. Although the theoretical models presented are different from each... 

To sum up, the contributions described above represent a few chosen examples of the experimental and theoretical work on the subject of quantum entanglement and coherence in condensed matter. This fascinating new field of science has not yet been given a common name. With no doubt it is, however, science "in statu nascendi" and as such needs further development. From the experimental point of view this new field needs new techniques involved. Some examples (NCS, neutron diffraction, ECS, IXS) have already been mentioned above. Further work is also clearly needed to make the theoretical models mentioned above more specific and directly applicable to the experiment. 

Keywords Quantum entanglement, sub-femtosecond dynamics, neutron Compton scatter-... 

Keywords Quantum entanglement, attosecond physics, Neutron Compton scattering... 

The research on quantum entanglement (QE) and decoherence, usually focuses on experiments and theory of quantum optics and optical traps involving single or just a few atoms. It is heavily dominated by the potential applica-... 

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