This is my recently published paper on vixra: http://www.vixra.org/abs/1311.0052 There's a lot of conceptual detail, but the jist of the experiment is like this, in the ZWM he combines the outputs of two downconversions (where a pump photon is converted to signal and idler of half the energy) by forcing one idler through the other crystal while its idler is also emitted. This somehow warrants the dropping of a mode in the calculation of the state vector (what an advantage). By dropping one idler mode he then calculates interference at the signal detector where the signals are combined. And he measures interference. Of note, we must recognize that Mandel has found a way around the no-communication theory (which roughly states that one cannot perform a measurement/operation on one member of an entangled pair that has measurable consequences on the entangled partner). Mandel has created an action (aligning the idlers with one penetrating the others region of emission) which is performed exclusively on the idler which has measurable results on the entangled partner (creating interference). And it is an action which is specifically not a measurement or operation. It is an action which changes the state description of the whole entangled system, and this change in the state description must be performed by the theoretician, it cannot be explicitly mathematically stated like an operation or measurement or POVM etc. I use this concept along with another concept he creates in an earlier paper with the same systems, the WZM. In this paper he also gets interference between the idlers by inducing stimulated downconversions in both crystals with a reference beam that is aligned with the signals. In this paper he uses a strong reference beam which is beamsplit and aligned with the two signal outputs of downconversion and it induces emission in the crystal, because it is of a sufficiently high photon occupation number. But I say that this implies something else, the high intensity quenches the signal output of the two signal beams with reference beam photons (that have identical description to the signals). This effectively makes it impossible to identify which photon, the originally entangled idler or one of many reference beam photons, is actually entangled with the idler. This effectively annihilates the entanglement or coincidental nature of the two photons. This is why the idlers are allowed to display interference regardless of the fact that the signals are available to have their path measured. In my proposal I combine the two concepts of the two papers induced coherence and coincidence annihilation to produce an instant communication prot
Uploading an article (on vixra) is not "publishing". In addition, vixra is a repository for crackpot papers. Why don't you submit to a mainstream journal? Because you keep getting rejections?
Because of the demands for referrals. I simply do not have any. So did you actually read the paper, or are you just an asshole who wants a problem and needs to exhaust his emotions on the internet. Hey, if that's what your into, I'm here for you. Bring it on Tach. Come to papa.
I glanced through the paper, and "implicit state determination" has no basis in quantum physics. If I understand you right, you're claiming that the math of quantum physics implies the photons from two aligned idler beams will always be indistinguishable. The theoretician, then, has to take the additional step of recognizing that the photons will be distinguishable if they arrive at different times. In fact, the original math captures this effect just fine. When we're talking about sending individual photons through an apparatus, it is often most convenient to work in a basis of "traveling wave" modes which are not eigenstates of the vacuum Hamiltonian. Such modes are time-dependent (hence the name "traveling waves"). Thus, the same process (in this case, passage through a downconverter) can put two photons into two different modes if they arrive at different times.
Just where did you get that idea? Parametric downconversion is a unitary process. Don't quote me on the details, but my recollection is that it can be modelled with a Hamiltonian that, very schematically, looks something like \(H \,\sim\, \kappa \bigl( a_{\mathrm{s}} \, a_{\mathrm{i}} \, a^{\dagger}_{\mathrm{in}} \,+\, a^{\dagger}_{\mathrm{s}} \, a^{\dagger}_{\mathrm{i}} \, a_{\mathrm{in}} \bigr) \,.\) Exponentiating this (or whatever the exact Hamiltonian is) gives a full, entirely unitary description of the parametric downconversion process. It's true that downconversion might very often be described in a much more simplified way in the theoretical part of many papers, but that's just the author making approximations and throwing away terms they don't care about. It's not because the full unitary description doesn't exist. Also, from the first page of your ViXra preprint: This is also wrong: "path (in)distinguishability" is fully describable within the standard mathematical formalism of quantum physics. It's not some extra rule or exception. Exactly what it means might vary from author to author, but generally speaking the translation into mathematical terms usually boils down to: "paths are indistinguishable" --> "system is in a pure state". "paths are distinguishable" --> "system is in a mixed state, diagonal with respect to the path states, possibly entangled with some ancillary quantum system".
I didn't submit anywhere else. No rejections. Are you angry that you didn't come up with such a great idea?
You must read the actual ZWM where Mandel states in the paper that he has dropped one idler mode due to the indistinguishability of the two idlers. This cannot be modeled with a unitary operation. You cannot operate on a state vector with an operator that will "drop one mode of the state vector". No such operator exists. The theoretician must intervene. Here is a free online copy of the paper; http://quantmag.ppole.ru/Articles/experiment/Mandel(1991).pdf The greatest physics paper ever written in history. Look at the second paragraph on the second page where he is quoted saying "If the downconverted modes i1 and i2 are perfectly aligned, then they may be treated as one mode." No operation required. No operation sufficiently describes this state determination. Your other point, Agreed, as long as we are only talking about a convention indistinguishability experiment, which clearly the ZWM is not. In the ZWM we have a form of indistinguishability that I call emission indistinguishability (one field is propagated through the region of emission of the other field at the time of emission), unlike the conventional measurement indistinguishability that you describe (upon measurement the two are permanently indistinguishable). I discuss both in the paper.
No, what I'm describing is what happens in the ZWM, here's a free online copy; http://quantmag.ppole.ru/Articles/experiment/Mandel(1991).pdf Look at the second paragraph on the second page where Mandel quotes "If the downconverted modes i1 and i2 are perfectly aligned, then they may be treated as one mode." No operation required. No operation sufficiently describes this state determination. This state determination is due to the nature of the indistinguishability of the two idlers. One idler is propagated through the region of emission of the other at the time of the other's emission. This exact time determines the center of the interference pattern and the determination of path lengths for the experiment (the path along s1 from crystal1 to the signal detector must equal the path along i1 to the second crystal and then along s2 to the signal detector). Although I do mention in the paper that this state determination is also contingent upon the signal photons being added at the detector in an indistinguishable manner, because they could have been used to distinguish the idlers otherwise, but of course the signals are added this way because it is they who interfere.
We might all note at this point that, if a state determination exists which has no explicit mathematical representation (which clearly the ZWM is a demonstration of such) then this type of state determination is not subject to the no-communication argument. As we all know, the no-communication argument (as trivial as it is) assumes an explicit state determination which is wholely explainable with operations and measurements. Alice's action is assumed to be explainable with a measurement on her system. The ZWM has no such measurement based action. The action of aligning or unaligning the idlers cannot be modeled with an operation. The question is, can we use such an implicit state determination in achieving instant communication? If you finish reading my paper you will see my full proposal.
Huh? That is an operation. A very simple one that maps the input mode \(\mathrm{i}_{1}\) to the output mode \(\mathrm{i}_{2}\): \(| \omega \rangle_{\mathrm{i}_{1}} \,\mapsto\, | \omega \rangle_{\mathrm{i}_{2}} \,.\) It's also an idealisation since, if I'm not mistaken, a photon in the input mode \(\mathrm{i}_{1}\) should also have a very small amplitude of itself undergoing downconversion and emerging as a photon pair (instead of a single photon in the \(\mathrm{i}_{2}\) mode). It's just that this amplitude is, as far as the experiment is concerned, completely negligible. So identifying \(\mathrm{i}_{1}\) with \(\mathrm{i}_{2}\) is an approximation, though one that's readily justified in terms of the general action of nonlinear crystals on photon states. The authors didn't just pull it out of nowhere. Generally speaking, any mapping of quantum states to other quantum states like this constitutes an operation, whether it's explicitly called that or not, so I really don't see where you're getting this "state determination outside the mathematical formalism of QM" stuff from.
OK, great, you call it a mapping and I call it an implicit state determination. Either way, it gets by the no-communication argument right? It has measurable consequences on its entangled partner photon. If i1 is mapped onto i2 then we calculate interference, but if i1 is not mapped onto i2 then we do not get interference. This would mean that there is a measurable difference in the reduced state vector of the entangled photon (the signal) due to the action that is taken on the idler. Hmmmm, doesn't no-communication theorem say that this is not possible? I believe it does. It looks like the ZWM has squeeked by the non-communication theorem.
No. If you have two entangled systems, A and B, then by performing different local operations on, say, the B system, you can introduce or affect interference effects in the joint statistics between A and B, or in the conditional statistics of A conditioned on obtaining a particular result when measuring system B (i.e. interference appearing following postselection). Examples of this sort of thing are routine nowadays. However, local operations on the system B never affect the marginal statistics you see in system A alone, because they don't change the reduced density operator describing system A. That's what the no-signalling principle says, and nothing about the ZWM experiment makes it an exception to that.
You seem to think that the ZWM is performing something like "interference appearing following postselection". In the ZWM it is the preparation of the idler photon which is the "conditional preparation" for the signal photon to display single photon interference. If the first idler emission is propagated through the region of the second and in alignment with the second then you get interference, otherwise you don't. It would be inappropriate to describe this as "joint statistics", it is single photon interference. It is entirely unlike that which is "routine nowadays".
I was making a general comment: the no-signalling principle shows that you can't manipulate part of an entangled system with local operations in a way that allows signalling. So either you only apply local operations and you won't see any signalling (and changes to interference patterns will only appear in joint statistics or following post-selection), or you can have signalling, but only by engineering an operation that is not local to one of the subsystems (which amounts to saying you can have signalling if you assume or arrange for it to happen it a priori). The ZWM experiment is actually of the latter type: the action of the NL2 crystal is not "local" to just the idlers, since it has the signal mode s[sub]2[/sub] as an output. It's via this that an operation on the i[sub]1[/sub] idler, before it reaches NL2, can wind up having an effect in the subsystem of signal modes. So they haven't "squeaked" anything. Mathematically, from the point of view of the no-signalling theorem, the choice of blocking or not blocking i[sub]1[/sub] is simply followed by an operation that is not local to the Hilbert space of idler modes. You can't, by the way, pretend that the NL2 crystal's mapping of the i[sub]1[/sub] mode to the i[sub]2[/sub] mode is something independent of the downconversion it induces on photons entering via the "V[sub]2[/sub]" path. It's a single component that does both: \(\begin{eqnarray} | 1 \rangle_{\mathrm{i}_{1}} | 0 \rangle_{\mathrm{V}_{2}} &\mapsto& | 0 \rangle_{\mathrm{s}_{2}} | 1 \rangle_{\mathrm{i}_{2}} \\ | 0 \rangle_{\mathrm{i}_{1}} | 1 \rangle_{\mathrm{V}_{2}} &\mapsto& | 1 \rangle_{\mathrm{s}_{2}} | 1 \rangle_{\mathrm{i}_{2}} \,, \end{eqnarray}\)among other things. Importantly, that this is a single operation (acting on a large Hilbert space) is what allows the i[sub]1[/sub] mode to get "mapped" to i[sub]2[/sub] in a way that preserves unitarity: the \(| 0 \rangle_{\mathrm{s}_{2}}\) and \(| 1 \rangle_{\mathrm{s}_{2}}\) (vacuum or single photon) signal states are orthogonal, so we have NL2 mapping different orthogonal input states onto orthogonal outputs, as it should. Put differently, information about whether an i[sub]2[/sub] photon came from i[sub]1[/sub] or V[sub]2[/sub] shouldn't be erased or destroyed, and it isn't: it ends up encoded in whether or not there's a photon in the s[sub]2[/sub] signal mode. This is fundamentally different from trying to "combine" the idler modes by some other means independent of NL2. For instance, if you tried to "combine" them with a beamsplitter (as the second figure in your paper seems to suggest you have in mind), then the action of the beamsplitter involves only the idlers and doesn't "couple" the signal and idler Hilbert spaces in the same way that NL2 in the ZWM experiment does, and the no-signalling principle is in full force.
OK, so we seem to agree on what the limitations are for the explanation of no-signaling theorem. It is usually not stated with this second alternative "engineering an operation that is not local to one of the subsystems". I like your analysis of the ZWM because you've combined the two mappings together at the second crystal (i1 to 12 and v2 to i2 and s2) in a way that has the orthogonal input and output states. This explains the "in principle knowability of path" in a way I haven't considered before. However this point, In the second figure I propose a different type of mapping is taking place. The idlers i1 and i2 are added at a beam splitter, and then they are transmitted through the region of a photon emission (say photoluminescence), call it e1, and in alignment with the emission (and the emission has an identical description/bandwidth to the idler). At the time of the emission of e1, I suggest an update to the total system state description which maps all three modes, i1 & i2 & e1, to the same mode, say i1. Why do I think this is enough to substantiate an update to the total description, because the intensity of the e1 emission is far greater than that of the idlers. The idlers are quenched by the emission. There is no way in principle to gain meaningful coincidence between signal and idler pair after the idlers have propagated through the e1 emission. For every idler (from either i1 or i2) there are many coincidental e1 photons in the same beam. So how do we distinguish which one is the original idler in coincidence with the signal. This type of reasoning is the only possible explanation of another paper that Mandel wrote, the WZM (figure 3 in my paper). In this paper he uses a reference beam that is identical in description to the signals of two downconversion crystals. The reference beam is beam split and transmitted through the crystals and in alignment with the signal outputs. However, because the reference beam is high occupation number, there is an induced coherence, so now all four outputs of downconversion are mutually coherent. Of course this is the reason why he gets single photon interference between the idlers in this experiment, the induced emission of downconverted photons, but it leaves out one obvious unanswered question. Why is it possible that the idlers produce interference while the signals are available to be measured? Should not the existence of the signal on a specific path infer the path of the coincidental idler, and erase interference? It doesn't work this way. The coincidental nature of the signal and idler is gone because the reference beam is of a high intensity (occupation number) so it quenches the signal beam. Mandel does not explain it this way (but I do in my paper), he shows that the visibility of idler interference is related to the "ratio of the occupation number of the reference beam divided by the bandwidth of the downconverted signal". In his picture the interference requires that "the stimulated downconversion outweigh the spontaneous downconversion". And his math is correct. But it is ironic that his math also points the finger at my argument. By rearranging the equation with the substitution of bandwidth=1/coherence length we arrive at a dependence of the visibility on the "product of reference beam occupation number to coherence length of the downconverted signal". This is basically "the number of reference beam photons per path times the path per signal photon" which is "the number of reference beam photons per signal photon". In my argument, the WZM has idler interference because of the reference beam quenching the signal beam. However, Mandel's argument has the mathematical explanation of the reference beam inducing emission of downconversion in the WZM, where as in my thought experiment I just have the two downconverted beams added and transmitted through the reference beam, e1. No mathematical picture. But does my picture of "coincidence annihilation" work anyway?
I should add, that in my picture I have assumed that the downconverted photons of signal and idler are not perfectly entangled in position, only in momentum. We have discussed this in a thread last year. For this apparatus that Mandel uses, there is perfect momentum entanglement, spontaneous parametric downconversion is a wavevector conserving process. So I assume that the average positions of signal and idler are entangled (to within a coherence length).
