> Il 5 giugno 2018 alle 5.05 Bruce Kellett <[email protected]> ha > scritto: > > From: <[email protected] mailto:[email protected] > > > > > > > On Tuesday, June 5, 2018 at 1:18:29 AM UTC, Bruce wrote: > > > > > > > From: <[email protected]> > > > > > > > > > > > > > > Remember that the analysis I have given above is > > > > schematic, representing the general progression of unitary evolution. > > > > It is not specific to any particular case, or any particular number of > > > > possible outcomes for the experiment. > > > > > > > > Bruce > > > > > > > > OK. For economy we can write, (|+>|e+> + |->|e->), > > > > where e stands for the entire universe other than the particle whose > > > > spin is being measured. What is the status of the interference between > > > > the terms in this superposition? For a quantum superposition to make > > > > sense, there must be interference between the terms in the sum. At > > > > least that's my understanding of the quantum principle of > > > > superposition. But the universe excluding the particle being measured > > > > seems to have no definable wave length; hence, I don't see that this > > > > superposition makes any sense in how superposition is applied. Would > > > > appreciate your input on this issue. TIA, AG > > > > > > > > > > > A superposition is just a sum of vectors > > > > in Hilbert space. If these vectors are orthogonal there is no > > > > interference between them. Your quest for a wavelength in every > > > > superposition is the wrong way to look at things. Macroscopic objects > > > > have vanishingly small deBroglie wavelengths, but the can still be > > > > represented as vectors in a HIlbert space, so can still form > > > > superpositions. I think you are looking for absolute classicality in > > > > quantum phenomena -- that is impossible, by definition. > > > > > > Bruce > > > > > > > > > > If that's the case, why all the fuss about Schrodinger's cat? AG > > > > > Is there a fuss about Schrödinger's cat? Whatever fuss there is, > > is not about the possibility of a superposition of live and dead cats. It > > is about choosing the correct basis in which to describe the physical > > situation. The Schrödinger equation does not specify a basis, and that is > > its main drawback. In fact, that observation alone is sufficient to sink > > the naive many-worlds enthusiast -- he doesn't know in which basis the > > multiplication of worlds occurs. > > Bruce > > "In this article, we demonstrate that we can measure the de Broglie wavelength of a two-photon wave packet (biphoton) with a Young double-slit experiment. The incident two-photon wave packet is generated collinearly from a nonlinear crystal by the process of spontaneous parametric down-conversion. The photons transmitted by the double slit form a fourth-order pattern which is a superposition of two Young interference patterns with different periodicity. One of them results from the interference of the individual photons (“the parts of the object” [in J. Jacobson, G. Björk, I. Chuang, and Y. Yamamoto, Phys. Rev. Lett. 74, 4835 (1995]) and has an oscillation period of lambda_0. The other pattern is due to the interference of the “object as a whole with itself,” i.e., the interference of the “biphoton” and shows a periodicity of (lambda_0) / 2."
Measurement of the de Broglie Wavelength of a Multiphoton Wave Packet E. J. S. Fonseca, C. H. Monken, and S. Pádua, PHYSICAL REVIEW LETTERS, 5 APRIL 1999, VOLUME 82, NUMBER 14 https://tinyurl.com/ya5rxn8a https://tinyurl.com/yatbb4ku -- You received this message because you are subscribed to the Google Groups "Everything List" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
