Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Somewhere in internet there is (where ?) a video showing the experiment, done in Venice during what it seems a Carnival event. To me, it has a slight taste of a joke, included the strange parabolic dish. I2LQF, Fabio On 04/05/2012 8.25, Erik Basilier wrote: Oh, and the first thing I looked at was whether it was in the April issue. It was not. Maybe the IEEE got it from another publication's April issue? -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Erik Basilier Sent: Thursday, May 03, 2012 10:10 PM To: elecraft@mailman.qth.net Subject: [Elecraft] OT: Distinguishable angular momentum in radio photons? The May 2012 issue of the IEEE Spectrum magazine reports that researchers in Italy and Sweden were able to conduct two separate instances of radio communication on the exact same frequency, without increasing bandwidth, and without time-division multiplexing, be making the transmissions differ in angular momentum. One transmission used linear polarization, and the other was given angular momentum by means of a dish with a radial cut, where the metal was bent backwards/forwards on the two sides of the cut. Apparently this is not just a case of linear vs circular polarization, as circular polarization can be readily picked up by a linearly polarized antenna, and apparently the two channels did not interfere with each other. The researchers claim that this demonstration points to the possibility that the radio photons can be given multiple, quanized levels of angular momentum, making possible several more communication channels without increased bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia describes MIMO as the technique of using multiple antennas as in diversity reception or in gain increases obtained by phasing the antennas. My apologies if this is too far OT. 73, Erik K7TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Well said Erik. My credentials do not match yours, but I do have a BS in Physics and made a living for 40 years as an Engineer. The theory may be bunk, but that is what most said about Einstein when he presented the Theory of Relativity. It sounds to me like a theory that is worth per-suing for someone. I don't think it is time to start pestering Wayne and Eric for a KX-31 yet, but inventing a detector for Angular Momentum might be an interesting research project for someone qualified. It is certainly a theory that is worth some minutes or hours of contemplation for me and for Erik as well, probably a lot of others on this august reflector. Theories are always ideas that someone is brave enough to present and risk being called a fool in hope that someone will prove he is a genius. Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Erik Basilier ebasil...@cox.net To: elecraft@mailman.qth.net Sent: Saturday, May 5, 2012 12:03 AM Subject: Re: [Elecraft] OT: Distinguishable angular momentum in radio photons? Eric, thanks for posting the link to the original article, and thanks also to the others who responded to my post. Since nobody complained about the subject, I guess I can make these comments before the thread gets to be too long and too OT. I did get one private email from a list member who felt I was a non-technical person writing about things way beyond my education. Just in case a lot of readers may feel the same way, let me explain to the list. I felt that the startling claims of the article would make for a more interesting conversation topic than some other discussions on the reflector. I related the gist of the article without personally trying to either support or debunk the content. I have a PhD in Physics as well as a Masters in Engineering from long ago, but I would not take myself so seriously as to spend the effort to try to arrive at a personal evaluation of a subject that the active researchers (pro as well as con) spent many hours on. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
On 05/04/2012 10:03 PM, Erik Basilier wrote: * The claim was not just that you can have two independent communications (as possible by means of circular polarization), but more than two. * The claim of multiple levels of angular momentum tells us that it is about OAM and not SAM. The abstract of the debunking research (thanks Sverre for posting) explicitly refers to OAM. Indeed photons can posses orbital angular momentum which can only interact with materials that have fairly special anisotropic properties (which is the reason I was not even bringing it up earlier). In order to talk to the oam component, one should subject RF photons to propagate in such medium as well. While possible in theory (and shown in optics using an obscure version of a halve wave plate), it would be a real challenge to observe this for RF where such materials are not available (someone correct me if I am wrong, I mostly work with optics). However, an interesting topic and well worth looking into! I wonder if photon orbital angular momentum would be conserved in a non-linear process where the difference and sum generation occurs (usually just the sum is used, for example in second harmonic generation; similar to RF heterodyning) and the difference component would lie in RF (OK, perhaps in GHz range in practice...; near baseband anyway ;-)? So the idea would be to start with optical photons (prepared with oam information) at close wavelengths and then convert to RF (RF wavelength = difference between the two optical photons; angular momentum must be conserved). Unfortunately, this would not work for detection that well because high intensities are needed for the non-linear process. I would expect that the first place where this would show up (if possible at all) for RF would be nuclear magnetic resonance (NMR) experiments where I could see that the extra source of angular momentum could find applications there. I suspect that most people are getting bored already - so I will sign off... Best, Jussi Eloranta AA6KJ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Lost or confused perhaps Jussi, but not bored! Keep it up, maybe we will learn something, maybe not! Willis 'Cookie' Cooke K5EWJ Trustee N5BPS, USS Cavalla, USS Stewart From: Jussi Eloranta jmelora...@gmail.com To: elecraft@mailman.qth.net Sent: Saturday, May 5, 2012 1:52 PM Subject: Re: [Elecraft] OT: Distinguishable angular momentum in radio photons? I suspect that most people are getting bored already - so I will sign off... Best, Jussi Eloranta AA6KJ __ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Oh, and the first thing I looked at was whether it was in the April issue. It was not. Maybe the IEEE got it from another publication's April issue? -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Erik Basilier Sent: Thursday, May 03, 2012 10:10 PM To: elecraft@mailman.qth.net Subject: [Elecraft] OT: Distinguishable angular momentum in radio photons? The May 2012 issue of the IEEE Spectrum magazine reports that researchers in Italy and Sweden were able to conduct two separate instances of radio communication on the exact same frequency, without increasing bandwidth, and without time-division multiplexing, be making the transmissions differ in angular momentum. One transmission used linear polarization, and the other was given angular momentum by means of a dish with a radial cut, where the metal was bent backwards/forwards on the two sides of the cut. Apparently this is not just a case of linear vs circular polarization, as circular polarization can be readily picked up by a linearly polarized antenna, and apparently the two channels did not interfere with each other. The researchers claim that this demonstration points to the possibility that the radio photons can be given multiple, quanized levels of angular momentum, making possible several more communication channels without increased bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia describes MIMO as the technique of using multiple antennas as in diversity reception or in gain increases obtained by phasing the antennas. My apologies if this is too far OT. 73, Erik K7TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
On 05/03/2012 10:10 PM, Erik Basilier wrote: The May 2012 issue of the IEEE Spectrum magazine reports that researchers in Italy and Sweden were able to conduct two separate instances of radio communication on the exact same frequency, without increasing bandwidth, and without time-division multiplexing, be making the transmissions differ in angular momentum. One transmission used linear polarization, and the other was given angular momentum by means of a dish with a radial cut, where the metal was bent backwards/forwards on the two sides of the cut. Apparently this is not just a case of linear vs circular polarization, as circular polarization can be readily picked up by a linearly polarized antenna, and apparently the two channels did not interfere with each other. The researchers claim that this demonstration points to the possibility that the radio photons can be given multiple, quanized levels of angular momentum, making possible several more communication channels without increased bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia describes MIMO as the technique of using multiple antennas as in diversity reception or in gain increases obtained by phasing the antennas. The only source of angular momentum in a photon is its intrinsic spin ( = 1). This can have two projections, +1 and -1 (only two, unlike for most spin one particles, which have three possible projections). However, these two projections are directly related to the left and right circularly polarized light, so I cannot quite see what other source of angular momentum could arise in this case? Having said this, I don't quite believe in the Swedish group explanation of this experiment. Jussi Eloranta AA6KJ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
I read a fairly comprehensive debunking of this some weeks/months ago, I just wish I could remember where I read it, it might have been in one of the physics publications I take at work, now probably buried under mounds of other stuff! I seem to recall that it picked up on pretty much the same points as Jussi has written. If I can find the source, I will post a link to it. 73 Stephen G4SJP On 4 May 2012 20:02, Jussi Eloranta jmelora...@gmail.com wrote: On 05/03/2012 10:10 PM, Erik Basilier wrote: The May 2012 issue of the IEEE Spectrum magazine reports that researchers in Italy and Sweden were able to conduct two separate instances of radio communication on the exact same frequency, without increasing bandwidth, and without time-division multiplexing, be making the transmissions differ in angular momentum. One transmission used linear polarization, and the other was given angular momentum by means of a dish with a radial cut, where the metal was bent backwards/forwards on the two sides of the cut. Apparently this is not just a case of linear vs circular polarization, as circular polarization can be readily picked up by a linearly polarized antenna, and apparently the two channels did not interfere with each other. The researchers claim that this demonstration points to the possibility that the radio photons can be given multiple, quanized levels of angular momentum, making possible several more communication channels without increased bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia describes MIMO as the technique of using multiple antennas as in diversity reception or in gain increases obtained by phasing the antennas. The only source of angular momentum in a photon is its intrinsic spin ( = 1). This can have two projections, +1 and -1 (only two, unlike for most spin one particles, which have three possible projections). However, these two projections are directly related to the left and right circularly polarized light, so I cannot quite see what other source of angular momentum could arise in this case? Having said this, I don't quite believe in the Swedish group explanation of this experiment. Jussi Eloranta AA6KJ __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
The C-band satellite has 2 channels on each frequency - I can't recall if one was horizontally polarized and th other vertical or whether one used right hand circular and the other left hand. In any case, it works and works quite well. So having 2 non-interfering non-multiplexed streams on one frequency is nothing new. 73, Don W3FPR On 5/4/2012 3:13 PM, Stephen Prior wrote: I read a fairly comprehensive debunking of this some weeks/months ago, I just wish I could remember where I read it, it might have been in one of the physics publications I take at work, now probably buried under mounds of other stuff! I seem to recall that it picked up on pretty much the same points as Jussi has written. If I can find the source, I will post a link to it. 73 Stephen G4SJP __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
This is the debunking saying that this is more or less a special case of MIMO - Multiple Input Multiple Output - communications, i.e. using multiple antennas on the rx and tx sides: Is orbital angular momentum (OAM) based radio communication an unexploited area? Ove Edfors and Anders J Johansson, IEEE TRANSACTIONS ON ANTENNAS AND PROPAGATION, 2012 http://www.lunduniversity.lu.se/o.o.i.s?id=12683postid=2062936 Abstract: We compare the technique of using the orbital angular momentum (OAM) of radio waves for generating multiple channels in a radio communication scenario with traditional multiple-in-multiple-out (MIMO) communication methods. We demonstrate that, for certain array configurations in free space, traditional MIMO theory leads to eigen-modes identical to the OAM states. From this we conclude that communicating over the sub-channels given by OAM states is a subset of the solutions offered by MIMO, and therefore does not offer any additional gains in capacity. - Sverre, LA3ZA K2 #2198, K3 #3391 LA3ZA Unofficial Guide to K2 modifications -- View this message in context: http://elecraft.365791.n2.nabble.com/OT-Distinguishable-angular-momentum-in-radio-photons-tp7525974p7528491.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Contact me if you would like a copy of this 2 page article. A New Twist on Radio Waves, IEEE Spectrum, Vol 9 (5), May 2012 /eric, kj7ae -- View this message in context: http://elecraft.365791.n2.nabble.com/OT-Distinguishable-angular-momentum-in-radio-photons-tp7525974p7528534.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
That sort of thing might work on VHF and above, but on HF it's my understanding that the polarization of the wave is altered in unpredictable ways by propagation through the ionosphere. 73, Ron AC7AC -Original Message- The C-band satellite has 2 channels on each frequency - I can't recall if one was horizontally polarized and th other vertical or whether one used right hand circular and the other left hand. In any case, it works and works quite well. So having 2 non-interfering non-multiplexed streams on one frequency is nothing new. 73, Don W3FPR __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Better yet, it's available free on-line: http://spectrum.ieee.org/telecom/wireless/a-new-twist-on-radio-waves /eric, kj7ae -- View this message in context: http://elecraft.365791.n2.nabble.com/OT-Distinguishable-angular-momentum-in-radio-photons-tp7525974p7528611.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Eric, thanks for posting the link to the original article, and thanks also to the others who responded to my post. Since nobody complained about the subject, I guess I can make these comments before the thread gets to be too long and too OT. I did get one private email from a list member who felt I was a non-technical person writing about things way beyond my education. Just in case a lot of readers may feel the same way, let me explain to the list. I felt that the startling claims of the article would make for a more interesting conversation topic than some other discussions on the reflector. I related the gist of the article without personally trying to either support or debunk the content. I have a PhD in Physics as well as a Masters in Engineering from long ago, but I would not take myself so seriously as to spend the effort to try to arrive at a personal evaluation of a subject that the active researchers (pro as well as con) spent many hours on. Without the intent of supporting or disproving the claimed results, and after reading the comments (but none of the original work), I make these basic observations: * Radio waves differ from light only by frequency, and are composed of photons if light is understood as composed of photons. * Photons have linear momentum although they don't have any rest mass. They also have two kinds of angular momentum, Spin Angular Momentum (SAM, with only two possible measured values), and Orbital Angular Momentum (OAM, which can have many). * The claim was not just that you can have two independent communications (as possible by means of circular polarization), but more than two. * The claim of multiple levels of angular momentum tells us that it is about OAM and not SAM. The abstract of the debunking research (thanks Sverre for posting) explicitly refers to OAM. * Debunking can have multiple meanings. Sometimes it can mean that the information in question is garbage. Sometimes it merely means that the information is not as new as claimed. In this case, the debunking might be of the second type (although I am not deeply enough in the issue to say it is). * Once one goes deep enough in physics, one finds that the laws of nature are just models that intend to mimic reality, and they are not reality itself. It may turn out that the claims made in this case bring nothing to our understanding, but there is not unusual in science to have situations where two theories explain the same phenomena in very different ways, and where neither theory can be pronounced incorrect. 73, Erik K7TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of erehm Sent: Friday, May 04, 2012 1:40 PM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] OT: Distinguishable angular momentum in radio photons? Better yet, it's available free on-line: http://spectrum.ieee.org/telecom/wireless/a-new-twist-on-radio-waves /eric, kj7ae -- View this message in context: http://elecraft.365791.n2.nabble.com/OT-Distinguishable-angular-momentum-in- radio-photons-tp7525974p7528611.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] OT: Distinguishable angular momentum in radio photons?
Very cool, Erik. There is a lot of astounding discovery taking place right now in physics. Another extremely weird relatively recent finding is vector potential (VP) radiation, in which communications are conducted not by actual photons but by virtual photons with zero power (the ultimate QRP) and cannot be received with metallic antennas; the antennas used are fluorescent bulbs from camping lanterns! All these secrets of the universe that continue to be discovered. Al W6LX __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] OT: Distinguishable angular momentum in radio photons?
The May 2012 issue of the IEEE Spectrum magazine reports that researchers in Italy and Sweden were able to conduct two separate instances of radio communication on the exact same frequency, without increasing bandwidth, and without time-division multiplexing, be making the transmissions differ in angular momentum. One transmission used linear polarization, and the other was given angular momentum by means of a dish with a radial cut, where the metal was bent backwards/forwards on the two sides of the cut. Apparently this is not just a case of linear vs circular polarization, as circular polarization can be readily picked up by a linearly polarized antenna, and apparently the two channels did not interfere with each other. The researchers claim that this demonstration points to the possibility that the radio photons can be given multiple, quanized levels of angular momentum, making possible several more communication channels without increased bandwidth. Other researchers say that this is just a form of MIMO. Wikipedia describes MIMO as the technique of using multiple antennas as in diversity reception or in gain increases obtained by phasing the antennas. My apologies if this is too far OT. 73, Erik K7TV __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
