> Il 3 agosto 2018 alle 0.56 Bruce Kellett <bhkell...@optusnet.com.au> ha > scritto: > > From: Brent Meeker <meeke...@verizon.net mailto:meeke...@verizon.net > > > > > On 8/2/2018 1:53 AM, Bruno Marchal wrote: > > > > > > > > > > > > > > > > On 1 Aug 2018, at 21:12, Brent > > > Meeker < meeke...@verizon.net mailto:meeke...@verizon.net > wrote: > > > > > > > > > > > > Indeed. But the common-cause explanation doesn't work > > > > for all choices of measurement angle. > > > > > > > > > > > > > > It does. Well, it does not if you assume only one Bob and > > > Alice, but the whole point is that it does if you take into account all > > > Alices and Bobs in the multiverse. > > > > > > > > Maybe you are not explaining your theory explicitly. > > > Aren't you assuming that there is a multiverse (essentially infinite) of > > > Alices and Bobs before this experiment; not just the few cases that arise > > > from the different experimental results. In this plethora of universes > > > there are many Alices measuring along 0deg and many Bobs measuring along > > > 27.5deg. That's how you get statistics...from this ensemble. > > > > > Something like that may be what is in Bruno's mind. But that > > clearly doesn't work either, because then we would have infinite numbers of > > unmatched Alice's and Bob's, and a major problem with non-local influences > > between disjoint universes in order to match any pair up. I think one can > > rule any such idea out very much more simply by just following the > > particles from a single entangled state to the respective experimenters. > > The statistics must work for such single-world pairs, so the invocation of > > infinite numbers of this or that is not actually going to help. > > Bruce >
LEV VAIDMAN, 'Teleportation: Dream or Reality?' 'Consider teleportation, say in the BBCJPW scheme. We perform some action in one place and the state is immediately teleported, up a local transformation (“rotation”), to an arbitrary distant location. But relativity theory teaches us that anything which is physically significant cannot move faster than light. Thus it seems that it is the classical information (which cannot be transmitted with superluminal velocity) about the kind of back “rotation” to be performed for completing the teleportation which is the only essential part of the quantum state. However, the amount of the required classical information is very small. Is the essence of a state of a spin-1/2 particle just 2 bits? I tend to attach a lot of physical meaning to a quantum state. For me, a proponent of the MWI, everything is a quantum state. But I also believe in relativistic invariance, so only entities which cannot move faster than light have physical reality. Thus, teleportation poses a serious problem to my attitude. I was ready to admit that “I” am just a quantum state of N ∼ 1030 particles. This is still a very rich structure: a complex function on RN. But now I am forced to believe that “I” am just a point in the R2N ?! The resolution which I found for myself is as follows: In the framework of the MWI, the teleportation procedure does not move the quantum state: the state was, in some sense, in the remote location from the beginning. The correlated pair, which is the necessary item for teleportation, incorporates all possible quantum states of the remote particle, and, in particular, the state which has to be teleported. The local measurement of the teleportation procedure splits the world in such a manner that in each of the worlds the state of the remote particle differs form the state by some known transformation. The number of such worlds is relatively small. This explains why the information which has to be transmitted for teleportation of a quantum state—the information which world we need to split into, i.e., what transformation has to be applied—is much smaller than the information which is needed for the creation of such a state. For example, for the case of a spin-1/2 particle there are only 4 different worlds, so in order to teleport the state we have to transmit just 2 bits.' hich I found for myself is as follows: In the framework of the MWI, the teleportation procedure does not move the quantum state: the state was, in some sense, in the remote location from the beginning. The correlated pair, which is the necessary item for teleportation, incorporates all possible quantum states of the remote particle, and, in particular, the state which has to be teleported. The local measurement of the teleportation procedure splits the world in such a manner that in each of the worlds the state of the remote particle differs form the state by some known transformation. The number of such worlds is relatively small. This explains why the information which has to be transmitted for teleportation of a quantum state—the information which world we 11 need to split into, i.e., what transformation has to be applied—is much smaller than the information which is needed for the creation of such a state. For example, for the case of a spin-1/2 particle there are only 4 different worlds, so in order to teleport the state we have to transmit just 2 bits. As for teleporting myself, the number of worlds is the number of distinguishable (using measuring devices and our senses) values of xi and pi for all continues degrees of freedom of my body -- 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 everything-list+unsubscr...@googlegroups.com. To post to this group, send email to everything-list@googlegroups.com. Visit this group at https://groups.google.com/group/everything-list. For more options, visit https://groups.google.com/d/optout.
