Counterfactual computation

[Jeroen Belleman]

John Larkin wrote:

On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:

[Snip!]

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.

If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.

That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman

 

[John Larkin]

On Wed, 29 May 2019 09:08:20 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:

[Snip!]


Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.

If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.

That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman

If they were independently random, you'd expect 1/4 of the
single-photon splits to fire both detectors and 1/4 to fire neither.

That doesn't happen. Those two cases both violate conservation of
energy. In a classical system, you'd get two photons at a longer
wavelength every time.

I think that QM and COE are deeply linked.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Jeroen Belleman]

John Larkin wrote:

On Wed, 29 May 2019 09:08:20 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:
[Snip!]


Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.
If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.
That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman

If they were independently random, you'd expect 1/4 of the
single-photon splits to fire both detectors and 1/4 to fire neither.

That doesn't happen. Those two cases both violate conservation of
energy. In a classical system, you'd get two photons at a longer
wavelength every time.

First of all, you can't shoot photons on demand. If you'd
use a pulsed source and adjusted the intensity to get
one detection event per shot on average, you *will* get
events with both or neither detector firing. I see no need
to invoke COE here.

Furthermore, in a classical system, splitting the beam
would get you two *waves* with half the power each, that
is, sqrt(2) times the amplitude, not twice the wavelength.
Waves aren't quantized in the classical model! A change
of wavelength requires a non-linear or a moving reflector.

What is typically done is to attenuate the light until
detection events are well-separated in time. (I'm assuming
the use of single-photon detectors, PMTs, SPADs, TES,
whatever. Mind you, a photon, to me, is not a discrete
particle that travels from source to detector, but only a
quantized interaction between EM waves and matter.)
You'll get irregular ticks out of your detectors, like a
Geiger counter.

Choose some time interval and count the number of events
over many such intervals. The number will vary randomly
with some mean and standard deviation. The standard deviation
converges on the root of the mean. In other words, both
detectors show full shot noise. If you histogram the data,
you'll obtain a Poisson distribution. The cross-correlation
of the number sequence for both detectors converges on zero.

I think that QM and COE are deeply linked.

I think that QM has a somewhat frivolous approach to COE.
Some even attribute the very existence of the universe
to a QM fluctuation, which is so far out that I can't
find a superlative strong enough to express my disbelief.

Jeroen Belleman

 

[John Larkin]

On Wed, 29 May 2019 09:48:59 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 11:31 PM, John Larkin wrote:
On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.



Sure. Fresnel coefficients derived from Maxwell's equations.

Fine if you don't believe in photons. Life is much simpler without
annoying things like shot noise.




--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[John Larkin]

On Wed, 29 May 2019 14:32:43 +0200, Jeroen Belleman
<jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 09:08:20 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:
[Snip!]


Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.
If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.
That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman

If they were independently random, you'd expect 1/4 of the
single-photon splits to fire both detectors and 1/4 to fire neither.

That doesn't happen. Those two cases both violate conservation of
energy. In a classical system, you'd get two photons at a longer
wavelength every time.

First of all, you can't shoot photons on demand.

I can reduce the intensity, or use a shutter, so that if I detect a
photon there is effectively zero chance that another is nearby. If
both detectors fire, COE has been volated.

Better yet, get one of those entangled photon sources and detect one
of them at the source. They you know where and when the other one
exists. Fire that into the splitter experiment.

All this sort of thing works better at shorter energies where
detectors are 100% efficient, hard xrays or gammas. Some of the poor
statictics of things like this are artifacts of noisy detectors. A
good gamma is as subtle as a bowling ball.

I don't think there is in principle no reason one couldn't invent a
clocked single photon emitter. Something similar has been done for
single electrons.





If you'd

use a pulsed source and adjusted the intensity to get
one detection event per shot on average, you *will* get
events with both or neither detector firing. I see no need
to invoke COE here.

Furthermore, in a classical system, splitting the beam
would get you two *waves* with half the power each, that
is, sqrt(2) times the amplitude, not twice the wavelength.

I said "longer wavelength."

Waves aren't quantized in the classical model! A change
of wavelength requires a non-linear or a moving reflector.

What is typically done is to attenuate the light until
detection events are well-separated in time. (I'm assuming
the use of single-photon detectors, PMTs, SPADs, TES,
whatever. Mind you, a photon, to me, is not a discrete
particle that travels from source to detector, but only a
quantized interaction between EM waves and matter.)
You'll get irregular ticks out of your detectors, like a
Geiger counter.

Choose some time interval and count the number of events
over many such intervals. The number will vary randomly
with some mean and standard deviation. The standard deviation
converges on the root of the mean. In other words, both
detectors show full shot noise. If you histogram the data,
you'll obtain a Poisson distribution. The cross-correlation
of the number sequence for both detectors converges on zero.


I think that QM and COE are deeply linked.

I think that QM has a somewhat frivolous approach to COE.
Some even attribute the very existence of the universe
to a QM fluctuation, which is so far out that I can't
find a superlative strong enough to express my disbelief.

Where did the universe come from?

Jeroen Belleman

--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Phil Hobbs]

On 5/29/19 6:50 AM, John Larkin wrote:

On Wed, 29 May 2019 09:08:20 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:

[Snip!]


Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.

If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.

That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman

If they were independently random, you'd expect 1/4 of the
single-photon splits to fire both detectors and 1/4 to fire neither.

Jeroen's talking about the _detector outputs_, because that's the only
place that the quantum character of light can be detected. Everywhere
else it just follows Maxwell's equations as one would expect. You
really can't reason correctly about light by visualizing little blurry
billiard balls.

That doesn't happen. Those two cases both violate conservation of
energy. In a classical system, you'd get two photons at a longer
wavelength every time.

Nope. You can't match the boundary conditions if the frequency
changes--phase matching is the key physics underlying the Fresnel
formulae. Maxwell's equations are a classical theory, after all.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 5/29/19 12:58 AM, John Larkin wrote:

On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:

On 29/5/19 1:31 pm, John Larkin wrote:
On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.

It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.

If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.

They get _detected_ on one side or another, which is another matter.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 5/29/19 12:54 AM, Clifford Heath wrote:

On 29/5/19 1:31 pm, John Larkin wrote:
On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources







I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality






When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.

It can, it does, and you can recombine them to get interference fringes.

No, it doesn't. It changes the EM boundary conditions, which changes
the field amplitude, and the photon detection rate goes as the power
density. Jeroen's quite right about the semiclassical model--you have
to work really hard to get any other result than full shot noise (or
worse, of course).

> That's kinda the point of wave-particle duality.

Photons aren't where that actually bites, because they aren't objects,
they're elementary excitations of the EM field in a given set of
boundary conditions. Doing interferometry with things like neutrons and
even buckyballs is where objects act like waves.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 5/28/19 11:31 PM, John Larkin wrote:

On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.

Sure. Fresnel coefficients derived from Maxwell's equations.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Phil Hobbs]

On 5/29/19 10:26 AM, John Larkin wrote:

On Wed, 29 May 2019 09:48:59 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 11:31 PM, John Larkin wrote:
On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.



Sure. Fresnel coefficients derived from Maxwell's equations.


Fine if you don't believe in photons. Life is much simpler without
annoying things like shot noise.

I have abundant data to show that a photon does not behave even slightly
like a billiard ball, and that with the exception of photodetection
statistics, classical EM theory is a complete description of the
propagation of light.

Cheers

Phil Hobbs


--
Dr Philip C D Hobbs
Principal Consultant
ElectroOptical Innovations LLC / Hobbs ElectroOptics
Optics, Electro-optics, Photonics, Analog Electronics
Briarcliff Manor NY 10510

http://electrooptical.net
http://hobbs-eo.com

 

[Jeroen Belleman]

John Larkin wrote:

On Wed, 29 May 2019 14:32:43 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 09:08:20 +0200, Jeroen Belleman
jeroen@nospam.please> wrote:

John Larkin wrote:
On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:
[Snip!]


Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.
It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

Clifford Heath.
If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.
That's not true. The detector outputs are independently random.
They are *not* anti-correlated. If they were, that would be
proof that light *is* carried by discrete particles, and we
don't have such proof.

Jeroen Belleman
If they were independently random, you'd expect 1/4 of the
single-photon splits to fire both detectors and 1/4 to fire neither.

That doesn't happen. Those two cases both violate conservation of
energy. In a classical system, you'd get two photons at a longer
wavelength every time.
First of all, you can't shoot photons on demand.

I can reduce the intensity, or use a shutter, so that if I detect a
photon there is effectively zero chance that another is nearby. If
both detectors fire, COE has been volated.

You can indeed reduce the intensity, reducing the probability
that both detectors fire for the same light pulse, but that
probability won't go to zero, not even with hypothetical perfect
detectors. (100% QE and no dark counts.)

Better yet, get one of those entangled photon sources and detect one
of them at the source. They you know where and when the other one
exists. Fire that into the splitter experiment.

All this sort of thing works better at shorter energies where
detectors are 100% efficient, hard xrays or gammas. Some of the poor
statictics of things like this are artifacts of noisy detectors. A
good gamma is as subtle as a bowling ball.

I don't think there is in principle no reason one couldn't invent a
clocked single photon emitter. Something similar has been done for
single electrons.

Single electrons, OK. Single photons, I don't believe it.
I'd love to be wrong.

If you'd
use a pulsed source and adjusted the intensity to get
one detection event per shot on average, you *will* get
events with both or neither detector firing. I see no need
to invoke COE here.

Furthermore, in a classical system, splitting the beam
would get you two *waves* with half the power each, that
is, sqrt(2) times the amplitude, not twice the wavelength.

I said "longer wavelength."

Waves aren't quantized in the classical model! A change
of wavelength requires a non-linear or a moving reflector.

What is typically done is to attenuate the light until
detection events are well-separated in time. (I'm assuming
the use of single-photon detectors, PMTs, SPADs, TES,
whatever. Mind you, a photon, to me, is not a discrete
particle that travels from source to detector, but only a
quantized interaction between EM waves and matter.)
You'll get irregular ticks out of your detectors, like a
Geiger counter.

Choose some time interval and count the number of events
over many such intervals. The number will vary randomly
with some mean and standard deviation. The standard deviation
converges on the root of the mean. In other words, both
detectors show full shot noise. If you histogram the data,
you'll obtain a Poisson distribution. The cross-correlation
of the number sequence for both detectors converges on zero.

I think that QM and COE are deeply linked.
I think that QM has a somewhat frivolous approach to COE.
Some even attribute the very existence of the universe
to a QM fluctuation, which is so far out that I can't
find a superlative strong enough to express my disbelief.

Where did the universe come from?

If only I knew. I have trouble believing the Big Bang,
despite the evidence. I suppose we all have. The
cosmological red-shift is strong evidence, but there
are too many unphysical ad-hoc patches in the model to
make it credible.

Jeroen Belleman

 

[John Larkin]

On Wed, 29 May 2019 11:37:19 -0400, Phil Hobbs
<pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/29/19 10:26 AM, John Larkin wrote:
On Wed, 29 May 2019 09:48:59 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 11:31 PM, John Larkin wrote:
On Tue, 28 May 2019 20:00:31 -0400, Phil Hobbs
pcdhSpamMeSenseless@electrooptical.net> wrote:

On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite:  "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that.  Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure.  You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade.  If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Cheers

Phil Hobbs

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.



Sure. Fresnel coefficients derived from Maxwell's equations.


Fine if you don't believe in photons. Life is much simpler without
annoying things like shot noise.

I have abundant data to show that a photon does not behave even slightly
like a billiard ball, and that with the exception of photodetection
statistics, classical EM theory is a complete description of the
propagation of light.

Cheers

Phil Hobbs

QM just redefines waves as the probability of having waves. That is
purely a mental game, but it seems to work.

The interesting non-destructive interaction of a photon/wave with
matter is the beam splitter.


--

John Larkin Highland Technology, Inc

lunatic fringe electronics

 

[Kevin Aylward]

"Jeroen Belleman" wrote in message news:qcemr3$1pap$1@gioia.aioe.org...

Yeah I can't really help that. Conceptually, it's not all that
different
than doing double slit interference 'one photon at a time'.
Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the particle
exploring all possible paths available to it. This happens to result in
the path of shortest time being the central white light fringe and path
differences of a few wavelengths having peaks of probability too.

Particles don't follow multiple paths at once.

Sure, they don't.

>Waves do.

Waves need a *physical* implementation.

Photons aren't
particles, they are quantized interactions between matter and EM waves.
There is no such thing as a discrete photon in transit.

That's pretty much a meaningless statement.

What, exactly do you claim the "EM Wave" is, physically, if not the photons
themselves? An Aether for light was rejected quite some time ago....hint MMX
experiment.

A standard wave is a disturbance in a medium. A physical wave without a
medium is pretty much nonsensical.

"Physical interactions" must be, essentially, by definition, interaction
between real physical objects. Declaring a wave is pretty much word salad
without identifying what it is.

There will never
be a pea-shooter for single photons at determined instants.

As far as results go, an individual pea shooter for photons have been
demonstrated many times.

https://en.wikipedia.org/wiki/Double-slit_experiment

"Interference of individual particles section."

The "Wave" either in QM or EM, does not appear to be physically real. It is
just way of accounting that it is a probability that particles have
observable values, that are not in agreement with values that deterministic
Newtonian Mechanics would predict. This is really the route, imo, of the
waffle of alleged existence of "waves". "Particles" do not follow newton's
laws. Motion has random components.

The universe is statistical. That statistical nature uses an equation. Its
unfortunate that this equation is called a "wave function". The reality is,
the Quantum Mechanical Wave function does not behave like a classical wave.
Indeed if it did, the Schrodinger Equation (non relativistically) would fail
to satisfy the Galilei Transformation, which would be problematic. (Quantum
Mechanics, A Modern Development - Leslie Ballentine p.103-p104)

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

 

[Kevin Aylward]

"Jeroen Belleman" wrote in message news:qck0ah$1u64$1@gioia.aioe.org...

On 2019-05-28 19:40, Phil Hobbs wrote:

On 5/24/19 11:15 AM, Jeroen Belleman wrote:
Jan Panteltje wrote:
On a sunny day (Fri, 24 May 2019 11:41:40 +0200) it happened
Jeroen Belleman <jeroen@nospam.please> wrote in
qc8e8j$b2t$1@gioia.aioe.org>:

My attention was drawn (by George, thanks!) to Kwiat's web page
below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources



I found a paragraph about "Counterfactual Computation" in there,
near the end. I cite: "... one can perform a measurement on a
quantum computer and obtain information about the solution to a
problem without the computer actually running". It's not even a
first-of-April article and they even managed to get it published
in Nature.

I suppose that if it doesn't need to be run, it doesn't need to
exist at all. Their funding money can be cut, too.

Jeroen Belleman

It is not the only weird statement I have come across about
'quantum'.

Well as long as we 'photon', 'spooky action at a distance', 'more
or less dead cats', and have supper and positions, OK I have
stated in an other group that it feels to me like a big hoax.
[...]

I'd agree, to a point. Classical physics works fine for light,
except for its interaction with matter. I'd like to see a
classical derivation of h.

ISTR that Planck had a good try at that around 1900.


The argument with the cats seems to deny that all quantum
effects are only detectable by statistics.

A single scintillation is detectable, but it's only statistically
_predictable_. The cat thing IIRC is an argument that you could have a
macroscopic object in a mixed quantum state--QM doesn't apply merely on
the atomic scale.

Cheers

Phil Hobbs


Even if the cat's lot is determined by some quantum event, it's
silly to pretend that its state is a superposition of all possible
states.

Not at all. The Quantum state is a probability state function, for example
P(x) which should not be confused with a classical state X.

A state such as

|psi> = |up> + |dn>

Means that, on measurement the result will either be |up> OR |dn> but not
both, as the vectors are orthogonal.

That may be a mathematically convenient way of treating
the problem, but in practice you'll always have one outcome per
event.

Sure, but not relevant to the interpretation of a superposition of states.

This so-called superposition is really just the admission of
our ignorance regarding the cat's fate. To pretend anything else
would be mysticism.

That interpretation, has been proven false. An ignorance interpretation,
essentially, means that there are hidden variables. Such a view seems
unlikely.

The Kochen–Specker (KS) theorem shows that unique values cannot be assigned
to observables prior to measurement.

https://en.wikipedia.org/wiki/Kochen%E2%80%93Specker_theorem

The probability distribution will become evident only after having
sacrificed a lot of cats.

Sure, but not relevant as to whether there are hidden variables that explain
an assumed ignorance.

I actually go over these issues here:

http://www.kevinaylward.co.uk/qm/quantum_mechanics.xht

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html

 

[whit3rd]

On Tuesday, May 28, 2019 at 9:58:37 PM UTC-7, John Larkin wrote:

On Wed, 29 May 2019 14:54:15 +1000, Clifford Heath
no.spam@please.net> wrote:

On 29/5/19 1:31 pm, John Larkin wrote:

Is there a classical explanation for the behavior of a half-silvered
mirror, a beam splitter? It can't split a photon.

It can, it does, and you can recombine them to get interference fringes.
That's kinda the point of wave-particle duality.

If you use two single-photon detectors after the splitter, you'll see
that each photon goes one way or the other. That's not very classical.

Big 'if' there; it isn't possible to both 'recombine them' AND use two detectors,
so the QM calculations are very different. If, by 'classical' you mean
real old-school light theories, neither single photon nor interference
are supported options...

 

[Jan Panteltje]

On a sunny day (Wed, 29 May 2019 21:23:36 +0100) it happened "Kevin Aylward"
<kevinRemovAT@kevinaylward.co.uk> wrote in
<ON-dncUtAYTWd3PBnZ2dnUU78QHNnZ2d@giganews.com>:

>The universe is statistical.

LOL

 

[Jeroen Belleman]

On 2019-05-29 04:16, George Herold wrote:

On Tuesday, May 28, 2019 at 8:00:36 PM UTC-4, Phil Hobbs wrote:
On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite: "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that. Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure. You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade. If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Phil Hobbs

Hmm, Let's say you're allowed some device with only probabilities.
So you push a button and one out of X times you get a photon.
If X was ten would that be a photon gun? (I'm thinking of single
atom/defect sources, some blast of laser light and a confocal microscope to
focus on one. X is the fraction of 2*pi steradians I can catch...
1/10th is probably too greedy.) Photons are created at 'atoms' and
destroyed/ detected at others. I don't see how having a single photon
gun is any different than a single photon detector.
(except the gun is harder technically. :^)

George H.

Good point. I think I was a bit too hasty with my 'definite answer'
statement. I'll have to think that over.

Jeroen Belleman

 

[George Herold]

On Thursday, May 30, 2019 at 8:19:16 AM UTC-4, Jeroen Belleman wrote:

On 2019-05-29 04:16, George Herold wrote:
On Tuesday, May 28, 2019 at 8:00:36 PM UTC-4, Phil Hobbs wrote:
On 5/28/19 3:18 PM, Jeroen Belleman wrote:
On 2019-05-28 19:46, Phil Hobbs wrote:
On 5/27/19 8:38 AM, Jeroen Belleman wrote:
Martin Brown wrote:
On 26/05/2019 19:44, Jeroen Belleman wrote:
On 2019-05-26 10:39, Martin Brown wrote:
On 24/05/2019 17:23, George Herold wrote:
On Friday, May 24, 2019 at 11:00:31 AM UTC-4, Jeroen
Belleman wrote:
George Herold wrote:
On Friday, May 24, 2019 at 5:41:46 AM UTC-4, Jeroen
Belleman wrote:
My attention was drawn (by George, thanks!) to Kwiat's
web page below:

http://research.physics.illinois.edu/QI/Photonics/research/#single-photon-sources






I found a paragraph about "Counterfactual Computation"
in there, near the end. I cite: "... one can perform
a measurement on a quantum computer and obtain
information about the solution to a problem without
the computer actually running". It's not even a first-of-April
article and they even managed to get it
published in Nature.
I'm not sure, but if you really cared you might write
and ask. I barely understand any of this stuff..
(non-linear optics and fancy x-tals.)

I don't care enough, maybe. The usual answer is 'shut up
and calculate', and indeed that works. What I have an
issue with is the unnecessary mysticism surrounding it
all.

I don't think the mysticism is entirely unjustified. It is
decidedly hard to interpret how Bell's inequality holds
without some difficulty. I would find it unacceptable to have
non-local variables with FTL communication as a get out of
jail free card for "explaining" QM.

https://en.wikipedia.org/wiki/Bell%27s_theorem#Original_Bell's_inequality





When we have a more complete theory it may be obvious how
entanglement actually works in detail, but at the moment it
looks a bit worryingly like Newton's classical gravity acting
at a distance with infinte speed.

Entanglement means that some aggregate property of an EM signal
is conserved across conversions. The LO and IF in a
super-heterodyne receiver are entangled, because you can
reconstruct the original RF by mixing them together again. This
is precisely what Zeilinger did with light in his article
"Imaging with undetected photons".


Yeah I can't really help that. Conceptually, it's not all
that different than doing double slit interference 'one
photon at a time'. Which is still kinda 'mysterious' to me.

In a handwaving sort of way you can visualise it as the
particle exploring all possible paths available to it. This
happens to result in the path of shortest time being the
central white light fringe and path differences of a few
wavelengths having peaks of probability too.

Particles don't follow multiple paths at once. Waves do. Photons
aren't particles, they are quantized interactions between matter
and EM waves. There is no such thing as a discrete photon in
transit. There will never be a pea-shooter for single photons at
determined instants.

Yes there is. And it has been done many times. With a suitably
dense filter and a monochromatic source you can do Young's slit
experiment so that there is never more than one photon in the
apparatus at a time. It became a lot easier to demonstrate once
Boksenberg's Image Photon Counting System became available which
does what it says on the tin. It has even been done in real time
at one of the RI Christmas Lectures.

This is completely beside the point. Of course you can attenuate
a light source so that the time between detections exceeds the
light-speed delay of the apparatus. Detection events will still
be random with a Poisson distribution. This behaviour can be
perfectly explained by a semi-classical model, where the probability
of detection depends on the power density of the incident wave.
No particle-like photons needed.

The impossible photon pea-shooter I was referring to was to
fire photons at a *regular* predictable rate. *That* is never
going to happen.

Not sure. You can make a reasonably regularly-spaced sequence of
quantum transitions via coulomb blockade. If you picked the right
transition, and arranged the geometry so that only one EM mode was
coupled to it, you might be able to do that.

Cheers

Phil Hobbs



That may end up with a device that shoots electron peas on demand,
but I'll admit I'm wrong only if someone manages to shoot photons
with it. Such a device would finally bring a definite answer to whether
it's either the field that is quantized, or rather just its interaction
with matter.

Jeroen Belleman


I'm with you there.

Phil Hobbs

Hmm, Let's say you're allowed some device with only probabilities.
So you push a button and one out of X times you get a photon.
If X was ten would that be a photon gun? (I'm thinking of single
atom/defect sources, some blast of laser light and a confocal microscope to
focus on one. X is the fraction of 2*pi steradians I can catch...
1/10th is probably too greedy.) Photons are created at 'atoms' and
destroyed/ detected at others. I don't see how having a single photon
gun is any different than a single photon detector.
(except the gun is harder technically. :^)

George H.

Good point. I think I was a bit too hasty with my 'definite answer'
statement. I'll have to think that over.

Jeroen Belleman

We sell a randomly timed single 'photon' source.
Small incandescent light bulb run at lower voltage... so it's mostly red.
Green interference filter (10nm BW, I think) And then some slits/ apertures.

George H.

 

[Jan Panteltje]

On a sunny day (Wed, 29 May 2019 21:23:36 +0100) it happened "Kevin Aylward"
<kevinRemovAT@kevinaylward.co.uk> wrote in
<ON-dncUtAYTWd3PBnZ2dnUU78QHNnZ2d@giganews.com>:

>The universe is statistical.

When looking at the Michelson and Morley experiment everybody was amazed.
I once asked in sci.physics about it and was given a simple calculation example
and that worked out OK.

But then...

What is this experiment? it uses reflected light.
What is reflected light?
Reflected light is _re_emitted_ light,
and thus locally recreated if you like that term.
Zero result!

Now could it be
20th century, poor fishsicks in school benches get zero result hammered into their heads.
No question asked, do not agree? tortured every day
by doing counter-intuitive 'Einsteinian math (also called relatitvitty or something).
Not agree? then no paper, more years of torture (or go cooking in restaurant
work at Michelson and Donalds ehh Mc Doughnuts, whatever),

So, in my view, I question that M&M experiment (though the M&Ms tasted OK just to get that straight).

And with that the whole card house by that Einstein comes crashing down.
AL of it
There IS an ether,
Time deletion, younger and older twins, it all goes out the window.
Just as silly as photon (from the same author Einstein).

For me, looking at these things as well as that kwantuun thingy, is just like
the Emperor has no clothes.

2019 today,

Einstein died and his last words apart from likely 'shit' was that the failed to unite graffity and
the rest of the world.
No wonder if you are stuck in math.
<copyright J.P.>

 

[Kevin Aylward]

"Jan Panteltje" wrote in message news:qcojf9$ada$1@dont-email.me...

On a sunny day (Wed, 29 May 2019 21:23:36 +0100) it happened "Kevin
Aylward"
kevinRemovAT@kevinaylward.co.uk> wrote in
ON-dncUtAYTWd3PBnZ2dnUU78QHNnZ2d@giganews.com>:

The universe is statistical.

When looking at the Michelson and Morley experiment everybody was amazed.
I once asked in sci.physics about it and was given a simple calculation
example
and that worked out OK.

But then...

What is this experiment? it uses reflected light.
What is reflected light?
Reflected light is _re_emitted_ light,
and thus locally recreated if you like that term.
Zero result!

The MMX experiment and its relation to SR is subtle.

Einstein introduced the idea of photons. If light was emitted as any ball
would be, relative to its source, then the MMX would obviously be NULL as
the source and observer were moving together.

So, the question is why did Einstein take the one key property that the
Aether gives, namely independence of the emitted speed from the source
velocity, that is bits of Aether vibrate hitting other bits of Aether
propagating an effect, at the characteristic speed of the medium, yet throw
the Aether itself away?

It is crucial to appreciate what Einstein actually said.

On the Electrodynamics of Moving Bodies:

"These two assumptions are quite sufficient to give us a simple and
consistent theory of electrodynamics of moving bodies on the basis of the
Maxwellian theory for bodies at rest. The introduction of a "luminiferous
ćther" will be proved to be superfluous in so far, as according to the
conceptions which will be developed, we shall introduce neither a "space
absolutely at rest" endowed with special properties, nor shall we associate
a velocity-vector with a point in which electro-magnetic processes take
place. "

Its the "superfluous" bit that is important. He doesn't say that it doesn't
exist. For the following reason.

Assuming the the equations of SR are correct, then those same equations show
that that if the Aether were actually there, they would explain why the
failure to detect such an Aether in the MMX experiment would occur. SR says
that the SR length contraction would result in a NULL result just as LET
would, despite an Aether being there.

I address that here:
http://www.kevinaylward.co.uk/gr/space-time-sanity.html

e.g

Einstein specifically stated:

"The theory of relativity belongs to a class of "principle-theories...As
such, it employs an analytic method, which means that the elements of this
theory are not based on hypothesis but on empirical discovery."

That is, physical hypothesis (mechanisms) are ignored from the outset, so
clearly makes no statement as to what those processes might be. Einstein is
directly declaring here explicitly, that he not not going to offer an
explanation, for example, a hypothesis as to why "sources could immediately
find a common speed". However, there is no suggestion or implication that
such a physical process does not exist.


Einstein, apparently, had a deep reason to hold on to independence of source
velocity, however, that bit that is not really the problem, its independence
of observer that is, although either one can be used to derive the other on
the assumption of all uniform motion being equivalent.

Independence of source velocity is a property of all wave motion, so in
itself, no big deal, if there is a medium.

Now consider a sun firing light at you. You travel into the sun and measure
its velocity. You now travel faster, yet you still measure the same
velocity.

The only way that can happen in the conventional universe is if your
measuring instrument properties are dependant on that velocity. This
directly implies that there is some sort of reference frame to which that
velocity is referenced.

Now could it be
20th century, poor fishsicks in school benches get zero result hammered
into their heads.
No question asked, do not agree? tortured every day
by doing counter-intuitive 'Einsteinian math (also called relatitvitty or
something).
Not agree? then no paper, more years of torture (or go cooking in
restaurant
work at Michelson and Donalds ehh Mc Doughnuts, whatever),
So, in my view, I question that M&M experiment (though the M&Ms tasted OK
just to get that straight).

I don't question the physical measurement result of the MMX, the issue is
its interpretation.

And with that the whole card house by that Einstein comes crashing down.
AL of it
There IS an ether,
Time deletion, younger and older twins, it all goes out the window.
Just as silly as photon (from the same author Einstein).

For me, looking at these things as well as that kwantuun thingy, is just
like
the Emperor has no clothes.

There is no reasonable doubt that the predictions of SR are correct. The
issue is why.

Someone taking a really fast trip will effectively travel into the future.
The word salad of standard SR says that the traveller "takes a longer path
in space-time". The alternative, is that there is an interaction with a
background frame that defines the physical process of clocks, such that
traveling at a velocity wrt a frame, truly results in processes slowing
down.

SR, to me, appears to be so specifically crafted to hide the physical
mechanism that makes it work. My take on "space-time" is also in


http://www.kevinaylward.co.uk/gr/space-time-sanity.html

-- Kevin Aylward
http://www.anasoft.co.uk - SuperSpice
http://www.kevinaylward.co.uk/ee/index.html