orbital angular momentum data transfer controversy

On a sunny day (Fri, 9 Nov 2012 16:11:57 -0800 (PST)) it happened Mr Stonebeach wrote in :

I will reply, because I wrote that, not Tucker. Somebody in sci.physics once argued that a 'quantum computah' could solve the traveling salesman's problem in next to no time.

I replied that if you take into account that noise, or translated to more mundane speak, the error rate of one quantum operation (25 % or so), and then do for example 1000 such operations, the probability of you 'solving' ANYTHING is less then the universe changing into a monkey as saying hello:-) And I think for this reason quantum computah has so far only factored the number

15 (fifteen) _with_help_..

It is an other one of those things. Not a day goes bye without some physics club claiming to have made a breakthrough that will bring quantum computahs so much closer. If you look at the source of all that shit, that for example a photon is not REALLY a particle, but just a wave disturbance (in the ether you you are so inclined), with an attack and decay time, then we are right at home with superpositions, multiplications (mixers), and all the stuff WE everyday play with and have many years of experience with, AND DITCHED for digital systems, as the 'analog computah', is not really THAT suitable to solve problems, its complexity would become staggering, not even to mention the word accuracy (well I did). So, a whole bunch of physisicks are pursuing a train of light particles, ever more pointing to the wave view, and phantasizing with that, and one day all that will be scrapped for the same reason we no longer use analog computers, and the photon concept will be dropped the same way. It is just one of those social projects for all the physisicks pushed out of the school benches after WW2 as the hope was they would make a better weapon (than the H bomb). Fed also crap, like the 'God particle' always tries to grab peoples attention as a huge breakthrough while in reality they have nothing but some numbers on a piece of paper. no fusion power, no new weapon, no energy source, no understanding, just a bunch of clowns that use ever more public money to write PhD tissue papers. Then there is the ignition facility that failed to make sustained fusion, now does that surprise me? Or anyone? they even locked up the guy who proved it could not work. So, industrial interests, buildings, suppliers, all US social projects that will never do anything useful. Now it goes to mil research. More madness, LIGO, ITER Germany finally stopped supporting it, thank God, and there are more of those things in the works. Electronics has brought us many fun things, not that we really need those, but usable in most cases, while all that crap physics has brought us nothing. And least of all a working quantum cmputah. And then there are those 2 guys calling themselves 'physicists', that claim they can send infinite extra info in a transmission channel. And they claim 'engineers do not understand this'. Well, probably true, trying to understand an idiot, if you succeeded would make you one no? So, we will wait for the demo of a thousand x the bandwidth at the same frequency with their system... Do not hold your breath. On the technical side you can look at what they propose as a screw with different turns per mm perhaps. By spacing antennas a turn apart you could get 2 maxima or minima. If you however slowly were to increase the number of turns per mm, "to get all modes' you soon would find that after 2n turns per mm you run into the same minimum duh. So it somehow seems that at 2 x there is some limit. But then I am not one of those physisicks, and if I cannot envision it I cannot understand it., And I cannot not envision what is there for all to see, the emperor has no clothes.

Its Saturday morning and I am not going to proofread this before posting. Have fun:-)

'Somebody' in the unmoderated group like sci.physics is not the Quantum Computing community. I'm almost sure you have talked to some amateur which has just read an article written by some popular science journalist without a clue.

mundane speak,

ving'

:-)

Yes of course. That is very well known by the QC community, but it may not be understood by an anonymous person posting to sci.physics.

Agreed, there have not been that impressive results from Quantum Computers, but the reason is not that those guys wouldn't understand what noise is or what Shannon theorem says. The reason is that the task is HARD.

You seem to be talking about quantum-gate based computers. The technique perhaps more likely to give some practical results soon is the Adiabatic Quantum computing, although it is not a "full" quantum computer. It just finds global minima in various optimization tasks.

I was a couple of weeks ago in a conference in Portland, where Richard Harris from D-Wave explained their AQC hardware. Their AQC finds the global minimum of a N-dimensional Ising system with freely programmable couplings. Harris claimed that many problems can be cast in the form of Ising system minimization, including image recognition problems tackled by Google Inc.

Their computation time scales as T[us] =5.84 N^2 + 65.5 N + 2E6 the function of the problem dimensionality N. This scaling does not come from a theory, but from the actual engineering of their functioning 128-qubit processor, the D-Wave One. For instance, the constant

2-second -term comes from the time it takes the system to cool back to the 20 millikelvin operating temperature, after the couplings are programmed through RSFQ circuitry. The programming cycle heats the system to 200 millikelvins. Lockheed Martin bought one D-Wave One system recently, I suppose not because it is practical, but because they want to stay at the edge of the developments in the field.

The classical supercomputers still perform the Ising system minimization faster then the D-Wave One, but the classical computational time increases ~exp(N), when using the fastest known Simulated Annealing or Iterated Taboo Search algorithms. Harris claimed that the break-even complexity is roughly N~2000, and that they are just about to roll out their 512-qubit D-Wave Two processor.

The stuff above are from Harris' talk, it sounds plausible to me, but I haven't studied all the details.All that stuff is pretty new to me, D-Wave has been criticized in the past about not telling the details of their work.

The rest of the drivel would take too long to comment, here's just one thing:

,

ing.

You don't count Bardeen's work as physics?

Regards, Mikko

limit.

Hi,

I guess there is no room for OAM in the theory of electromagnetic waves if it really does propagate as transverse waves, and the typical way to get a corkscrew effect is to superimpose two orthogonal transverse waves that are out of phase to make the elliptical polarization, this causes the pseudo OAM by having the vector of the E field and M field from the two orthogonal transverse waves rotating.

If physicists think there is such a think as fundamental OAM, they must think light doesn't propagate as a transverse wave then I guess, that would be interesting if light transverse waves could corkscrew I guess, maybe there is a way to do that.

cheers, Jamie

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OAM is not the same as superimposed orthogonal transverse polarizations, nor circular polarization.

Typically, optical OAM beams are generated using fork holograms:

For RF, one way is to take a dish reflector and cut it from center to edge, then displace one edge in the direction of propagation and the other edge "backwards" so to speak; IOW make it a sort of slice of a corkscrew:

from:

Mark L. Fergerson

The issue was whether two photons from distinct sources could interfere at all. How they explained the superhet I have no idea.

BTW I entirely agree about light vs. radio. It's amazing the number of tricks from early radio can be used profitably in electro-optical instruments.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

There must be a super-regen laser mode: ramp up the pump until it lases, detect that, shut down, repeat. An extra external photon or two will change the rep-rate. Like the super-regen, it will radiate. And do very narrowband FM slope detection.

--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators

limit.

Using multiple modes is a perfectly fine way to get more capacity, if you can keep them straight. It just isn't what the twisty folks think they're doing.

BTW optics folks have known about these modes for yonks--field distributions with nulls in the centre and helical phase are called "optical vortices".

I first encountered one in a microscope I designed in cooperation with some guys from Sira Ltd in the UK, back in 1990 or so. It was the first silicon immersion microscope, based on contacting a silicon plano-convex lens to the back of a silicon wafer. (A technique that has become widely used since then.) It was to use a pressurized air bearing with

50 nm clearance to allow scanning and reduce surface damage. That 50 nm was enough to lose a lot of light by total internal reflection, but interestingly it turned out to be possible to overcome the problem by switching to tangential polarization, where the E field direction was always perpendicular to the plane of incidence no matter where you were on the lens. This was accomplished using a segmented half wave plate, shaped like an 8-petal daisy, which generated a very creditable approximation of tangential polarization.

We were very proud of this idea, until we noticed that the resulting focused spot would have a null at the centre, i.e. the spatial resolution would be horrible. (The different segments would be trying to have it point in every direction, and none would win.) That was an example of an optical vortex, maybe the first one in a technological example, I don't know.

We straightened it out by applying a coating of 1/8 wave to segment 1,

1/4 wave on segment 2, up to 1 wave on segment 8, so that the phase advanced by one cycle as you went round the pupil. That replaced the central null with a circularly-polarized peak, and cleaned up the resolution amazingly.

The design was all finished and ready for production by early 1992, at which point IBM very nearly went bankrupt, and both our budget and our customer went away. I still have all the drawings, though. If it were built today, it would still hold the lateral resolution record in silicon by about a factor of 2 over any current instrument. (It ran at a numerical aperture of 6.4.)

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

I've been wanting to do that for ages, but every time I get what looks like the right application, it turns out to be a force fit, and I have to do it another way. One reason is the huge chirp you get in a cleaved-cavity laser as it turns on.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net

Hi,

Those are neat, I think they are used in special electron microscope to give the electron beam angular momentum for allowing different types of sample measurements to be done, but the efficiency and amount of angular momentum is limited with that technique. I didn't know they can work on light too!

cheers, Jamie

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Wow, Nice story! Thanks

I'm going to have to ask for a pic of the 8-petal daisy, on some bar napkin, when I buy you one. (alternating segments of 1/2 wave plates?)

It keeps getting better, (sounds expensive?)

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How many good designs are in drawers somewhere?

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I'm reminded of laser intra cavity absorption, which is different, but similar.

George H.

I can name at least two, though they'd take quite a lot of updating. Twenty years is a long time in electronics.

--
Bill Sloman, Sydney

Hi,

That is really neat! I guess the E field is radial to the beam on the perimeter and then axial with the beam in the center of the beam? I'm pretty sure I have no idea how it works, but thanks for sharing that, something neat about the words "optical vortex" :)

cheers, Jamie

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Neat, indeed. I posted the stuff showing the linkage between optical and RF EM vortices because I was disheartened by what I saw as a combination of the Not Invented Here attitude and misinterpretation that some people seem to have about physicists' "laboratory curiosities". Nice to know people like Phil are doing some fairly sophisticated physics while pursuing practical goals.

;>)

Mark L. Fergerson

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It's also nice to see a physicist like Phil doing some fairly sophisticated electronics while pursuing practical goals. Rev.Sci. Instrum. publishes some fairly diabolical electronics from time to time.

The U.K.'s "Measurement Science and Technology" isn't as bad, perhaps because they publish more stuff reporting commercial instruments, and seem to use those authors for refereeing - I've looked at the occasional paper for them, though nothing much recently.

--
Bill Sloman, Sydney

Hi,

I have heard a similar idea about OAM in the past for explaining what matter is made of. If you had enough OAM in a small enough space for light, it will possibly have strong enough field strength to hold itself together, and create matter. Not sure if that is already part of the e=mc^2 but it probably is.

cheers, Jamie