Tunneling

Yeah I thought about that. Check out figures 5 and 6 here,

For the low voltage ones the TC is about the same as a 'normal' diode ~ -2mV/K (but becomming smaller at lower current???) I read in Sze that the TC for tunneling is due to the change in band gap with temperature. (But I've forgetten what causes the TC in a normal diode... is it also the band gap?) Then you see in figure 6 that somewhere around a 6V zener you get +2mV/ K... and a 6V zener plus diode in series gives you a zero TC voltage reference.

George H.

I don't see a real difference in principle. The avalanche takes place in a gas rather than in a solid. It detects charged particles much more readily than gamma radiation, although it will do that too.

To detect gamma radiation, it has to hit something material and the detection process is again discrete and probabilistic. Good luck in performing the double-slit experiment though.

Jeroen Belleman

A photon doesn't have enough of the required properties to qualify as a 'thing', i.e. something self-existent. It's an elementary excitation of the EM field in a certain set of boundary conditions, not an object like a rock or an electron. We've gone over this several times in sci.optics, e.g.

.

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

That's my whole point! You are not counting photons, you're counting ionization events which occur with a probability proportional to the local EM power. At very low intensities, the interference pattern is there, but it will cause detection events only occasionally. If you really want to have photons, reserve the word for the amount of energy that is exchanged between the field and a particle. At least that's local and essentially instantaneous, doing away with all these non-locality problems.

Is it really so mysterious that the EM waves created by parametric down conversion have certain collectively conserved quantities? A BBO crystal is basically an array of tiny non-linear harmonic- injection-locked resonators. No need to think in terms of photons to explain its operation.

Jeroen Belleman

On 26/03/13 20.25, Phil Hobbs wrote: ,,,

Truth about photons:

Glenn

;)

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

George Herold Inscribed thus:

Some of the electrodes in tubes and crt's are made from nickel.

--
Best Regards: 
                        Baron.

Battery-connection straps are nickel. 1955-1981 Canadian nickels are nickel.

--
Cheers, 
James Arthur

e e n

Yeah sure, I'm basically agnostic on whether photons are 'real'. (It doesn't matter to me one way or other.) To me they are as real as lattice vibration phonons*. I don't totally understand either, but it's a darn useful concept for thinking about things (and getting the right answer).

George H.

*or all the other 'nons in solid state phyiscs.

What about squeezed states of light? If your transmitter sends eg. a photon-bunched state, rather than the coherent state, and you notice at the receivcer end that your counting statistics change - shouldn't the field somehow carry information about what statistics the transmitter uses?

Regards, Mikko

Hi Jeroen,

I don't want to argue, but rather try to understand. You have obviously put some thought on the light-matter interaction puzzles. However, as much as I dislike the whizzing-ball picture of photons, I'm wondering whether it is possible to discard the photon concept (in the sense used by eg. Louisell, or Glauber) in as radical a way as you seem to suggest.

For example, in superconducting transition edge sensors the smallest excitation is *much* smaller than the energy of absorbed photons. Then it must be some other mechanism than the physics of the

*detector* which forces the EM energy being absorbed in the lumps of the size omega hbar.

An example is the work of Aaron Miller et al

From the detector physics point-of-view, they

*would be* capable to see two 0.4eV events, or three 0.27eV events when shining a 1.55um laser on the detector - but they never see those, only single 0.8eV events. Or, more accurately: they see the Poisson distribution, characteristic of a coherent state being received.

Now, assume that a detector with a different composition (say, an APD - although I don't know offhand if they have sufficient energy resolution) is detecting the same phenomenon. If it, too, sees only single 0.8eV events and not any double

0.4eV events, wouldn't it be more natural to ascribe the 'lumpedness' as a property of the EM field rather than the property of the detector?

In particular, if you shorten the wavelength of the illuminating laser (i.e. change something in the transmitter side), you see that the size of absorbed energy lumps goes up. Now, detector physics (including the detectors excitation spectrum) supposedly does not change, still the lump size it sees changes. Wouldn't it in this case be more natural to associate the lump size to either the transmitter or the EM field, rather than to the detector? (OK, I suppose you can answer 'it is the transmitter', but then a similar argument about a transmitter of any physical composition can be constructed).

I do agree that the photon absorption phenomena *could* be explained by a postulated physical phenomenon which always occurs at the light-matter interaction, and which always gives the lump size of hbar-omega regardless of the detector physics (solid state, gas ...) and regardless of the range of energy excitations available in the detector (semiconductor gap, superconducting gap, continuous spectrum of thermal excitations...). But isn't such a postulate much more awkward than accepting the discreteness to be a feature of the EM field itself (in the Louisell sense)?

I think single-photon sources *do* exist, but I better not make that claim too strongly before refreshing my memory on the subject. There has been a review, I must dig it out...

At least: non-poissonian photon sources *do* exist (e.g bunched or anti-bunched); whether there are externally triggerable ones nowadays I'm not sure.

I remember being intriguiged in late-90's by claims that an ordinary LED, when driven by sub-poissonian current, would act effectively as single photon emitter. The question is of course how to create that sub-poissonian current, in particular when there is the junction capacitance present. I should dig out those old papers as well...

Regards, Mikko

n

Does this 'conserved quantity' way of thinking really work if one puts it to a closer scrutiny? To me it sounds like you're giving the classical EM field the role of 'hidden variables' in the Bell sense.

I mean, saying that "the EM field propagates as wave but is absorbed in a discrete way" *does* resembles the QM description where wave function propagates in an unitary manner but collapses at the measurement. Still, the connection must be made in a more clever way IMO than just kind of stating that the classical EM field somehow *is* the wave function.

In the standard prescription one must replace the field variables E, B by field operators, and all the standard QFT yada yada - *then* you can account for all the nonclassical experimentally verified phenomena such as GHZ states, but thereby also the concept of photon creeps in, in the form of the discrete excitations of the harmonic oscillator. And this is a part of the EM field, not a part of the detector or the transmitter physics.

Regards, Mikko

Hi Mikko,

Thank you for your comments. APDs have no energy resolution and no ability to distinguish multi-photon events worth mentioning. I wasn't aware of Aaron Miller's work, but it looks closely related to the photo-electric effect, for which a semi-classical analysis appears to work. It's much better that the photo-electric effect in the sense that there is no energy lost to the work function.

Regards, Jeroen Belleman

er not

e.g

that

? ? ? ?Mikko

Hi Jeroen,

Let me still add the link to the photon source review I had in mind:

.

I only found one LED emitter reference (from a seminar talk I gave as a grad student in -97 about QND measurements):

but that is not the one I'm thinking - authors were japanese in that paper.

Regards, Mikko

Found it, it's the ref. 5 in the Roch-Poizat-Grangier paper:

(and the authors are not japanese - I must have been thinking Yamamoto's work).

The experiment looks even more fishy (wonderful) than I remebered. Although the effect they see is small.

Regards, Mikko

Wow... excellent, I wonder if I can still find some in circulation if I go to Canada.

George H.

Some Japanese guys back in the 80s got a couple of dB of amplitude squeezing by doing that with a diode laser, iirc.

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

Ni-NiO-Ni tunnel junctions have barrier heights of about 0.2 eV. This behaviour in nickel is why nickel plated BNC connectors tend to be flaky with low level signals.

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

Oops, googling Ni-NiO tunneling (item #3)

Not to be critcial, but the I-V looks ~90% resistive, and worse at room temperature.

George H.