spooky communication

Ian Macmillan

Reading about Nicholas Gisin's experiments with entangled photons at
significant distances leads me to ask the following:

Assume a down converting source of entangled photons that sends the divided
stream to two locations through unequal length arms.

If the photons arriving at the end of the shorter arms are all directed to a
vibrating absorber, (e.g. a lamp blacked loudpeaker diaphragm) , all the
incoming photons should be frequency modulated as they are absorbed, due to
the motion of the diaphragm.

1. Would this frequency modulation be apparent at a detector at the end of
the longer arm?

2. If (1) is so, why would this not facilitate faster than light
communication?

All the best

Ian Macmillan

scerir

> 2. If (1) is so, why would this not facilitate faster than light
> communication?
> Ian Macmillan

The first answer would be that quantum correlations
are a-causal. Since this answer is not completely
satisfactory, you would ask: "What if we try to introduce
a tiny bit of causality in those quantum correlations?".
This question might be interesting but - I suppose -
the answer would be that if we introduce a tiny bit
of causality ... the correlations become less correlated,
and you see no effect at all. (About this specific
point there is some literature, papers by Zeilinger,
Greenberger, etc.).
s.

Bob_for_short

On Dec 26, 9:05 am, Ian Macmillan <iand...@tpg.com.au> wrote:
> Reading about Nicholas Gisin's experiments with entangled photons at
> significant distances leads me to ask the following:
>
> Assume a down converting source of entangled photons that sends the divided
> stream to two locations through unequal length arms.
>
> If the photons arriving at the end of the shorter arms are all directed to a
> vibrating absorber, (e.g. a lamp blacked loudpeaker diaphragm) , all the
> incoming photons should be frequency modulated as they are absorbed, due to
> the motion of the diaphragm.
>
> 1. Would this frequency modulation be apparent at a detector at the end of
> the longer arm?
>
> 2. If (1) is so, why would this not facilitate faster than light
> communication?
>
> All the best
>
> Ian Macmillan

1. No. The detected frequency is determined with the absorber velocity
which does not influence the photon source.
So the other arm photons arrive non modulated.

Bob.

Ian Parker

I think you are looking at the problem the wrong way. If we say

H(phi) = E(phi)

We have expressed the basic QM equations in Hasmiltonian form.

What happens if we impose a vector Vsin(wt) on H.

We clearly get :-

1) The possibilty of transitions between quantum states.

2) If quantum states are close together (as they are in the slit
experiment) you will observe this as a modulation. There are
transitions between quantum states. This can be readily appreciated if
we consider the doppler effect and the fact that light will be shifted
in frequency.

FTL? No way. All the equations are transformation with the Lorentz
matrix (if we view the thing in another FOR) and FTL is impossible.
You might well obseve an FTL phase velocity, but there is nothing
startling in this. After all the ionosphere has a negative refractive
index. If you modulate continuously you see FTL phases. If you start
you will not observe anything till cd time has elapsed.


- Ian Parker

ilper@abv.bg

On 26 Dec, 10:05, Ian Macmillan <iand...@tpg.com.au> wrote:

> 1. Would this frequency modulation be apparent at a detector at the end of the longer arm?

As this way of modulation you are envisioning constitutes a
measurement on the photon you will receive a 50/50 left/right
polarization for the partner-photon and of course no change in the
lambda.
I think it is possible to achieve a frequency modulation but on the
spin (polarization?) vector. If one has an entangled pair of electrons
one can by applying a magnetic field rotate the direction of the spin
of one of the partners of the pair. Notice that this modulation will
be transfered to the beam in the long arm. So it can be that way
delivered anywhere.

> 2. If (1) is so, why would this not facilitate faster than light
> communication?

If one tries to measure the spins in the long arm he nevertheless will
receive a 50/50 up/down distribution and consequently no FTL
communication. But the spins of two partners will be definitely in
opposite directions.

Regards: Ilian

Ian Parker

I think you are looking at the problem the wrong way. If we say

H(phi) = E(phi)

We have expressed the basic QM equations in Hasmiltonian form.

What happens if we impose a vector Vsin(wt) on H.

We clearly get :-

1) The possibilty of transitions between quantum states.

2) If quantum states are close together (as they are in the slit
experiment) you will observe this as a modulation. There are
transitions between quantum states. This can be readily appreciated if
we consider the doppler effect and the fact that light will be shifted
in frequency.

FTL? No way. All the equations are transformation with the Lorentz
matrix (if we view the thing in another FOR) and FTL is impossible.
You might well obseve an FTL phase velocity, but there is nothing
startling in this. After all the ionosphere has a negative refractive
index. If you modulate continuously you see FTL phases. If you start
you will not observe anything till cd time has elapsed.


- Ian Parker

Ian Parker

On 29 Dec, 13:26, il...@abv.bg wrote:

> I think it is possible =A0to achieve a frequency modulation but on the
> spin (polarization?) vector. If one has an entangled pair of electrons
> one can by applying a magnetic field rotate the direction of the spin
> of one of the partners of the pair. Notice that this modulation will
> be transfered to the beam in the long arm. So it can be that way
> delivered anywhere.

You can modulate by any method you choose. The same fundamental
arguments apply. You can do a very simple thing with spins, you can
apply a magnetic field and one spin direction vibrates faster than the
other. What you have done though is to produce a hyperfine structure.
If you apply an oscillating magnetic field you have in fact an
identical situation to the one I described in my last posting.
>
> > 2. If (1) is so, why would this not facilitate faster than light
> > communication?

Let me put it this way. If you were to put your apparatus in a box and
put it into another FOR you would have a time machine. This is the
natrure of paradox. A physical box that moves is "gedanken". You can
do the same thing though by doing a unitary transformation.
>

- Ian Parker

Tom Roberts

Ian Macmillan wrote:
> Assume a down converting source of entangled photons that sends the divided
> stream to two locations through unequal length arms.
> If the photons arriving at the end of the shorter arms are all directed to a
> vibrating absorber, (e.g. a lamp blacked loudpeaker diaphragm) , all the
> incoming photons should be frequency modulated as they are absorbed, due to
> the motion of the diaphragm.
>
> 1. Would this frequency modulation be apparent at a detector at the end of
> the longer arm?

No. The entangled state of the photons does not include such modulation.
Remember that frequency is NOT an intrinsic property of a photon.

But spin is [#]: had you measured the orientation of the spin of the
photon at the shorter arm, you would immediately be able to predict with
certainty the outcome of a corresponding measurement at the other arm
(i.e. along the same spatial axis you used). But this is not FTL
communication, because you are not located at that arm, and
communicating your knowledge to the other arm is limited to lightspeed.

[#] speaking loosely: the magnitude of its spin is intrinsic
to the photon, but its orientation is only statistically so.
But that's good enough here.


> 2. If (1) is so, why would this not facilitate faster than light
> communication?

Because you still need to communicate to the other arm. Your inability
to predict the outcome of your measurement prevents you from using this
correlation of spins to transmit information.


Tom Roberts

Ian Macmillan

"Bob_for_short" <vladimir.kalitvianski@wanadoo.fr> wrote in message
news:3ce37c23-1d7d-4f02-bfe5-16c63fc013c5@g3g2000pre.googlegroups.com...
> On Dec 26, 9:05 am, Ian Macmillan <iand...@tpg.com.au> wrote:
> > Reading about Nicholas Gisin's experiments with entangled photons at
> > significant distances leads me to ask the following:
> >
> > Assume a down converting source of entangled photons that sends the divided
> > stream to two locations through unequal length arms.
> >
> > If the photons arriving at the end of the shorter arms are all directed to a
> > vibrating absorber, (e.g. a lamp blacked loudpeaker diaphragm) , all the
> > incoming photons should be frequency modulated as they are absorbed, due to
> > the motion of the diaphragm.
> >
> > 1. Would this frequency modulation be apparent at a detector at the end of
> > the longer arm?
> >
> > 2. If (1) is so, why would this not facilitate faster than light
> > communication?
> >
> > All the best
> >
> > Ian Macmillan
>
> 1. No. The detected frequency is determined with the absorber velocity
> which does not influence the photon source.
> So the other arm photons arrive non modulated.
>
> Bob.
>
I have to say that I am confused about the term "a-causal" from "s", which I
understood to mean "without cause", or lately in arbitrary time assignment,
to refer to where an event is influenced by a "future" condition. I confess
ignorance about the introduction of causality in this context.

But I also do not understand Bob's point about the absorber velocity not
influencing the photon source. Surely when the photons are absorbed they are
just photons, and do not indicate the relative velocity of the source and
absorber, unless there is prior knowledge of this.

I thought that the two photons of a conjugate pair form a separated entity,
about which nothing can be determined until one or the other is measured.
So, if one is measured to be bluer, the other might be expected to be
redder, because when defined by the detection of its conjugate, the total
energy of the pair should be conserved.

I would not expect non-entangled split streams of photons to behave in this
way.

I claim much ignorance in this area, but feel that there should be
difference between the bulk behavior of entangled and un-entangled divided
streams.

All the best
Ian Macmillan

scerir

Tom Roberts:
> But this is not FTL communication, because
> you are not located at that arm, and
> communicating your knowledge to the other arm
> is limited to lightspeed.

This is only partially true :-) You can imagine
the observer located at wing A (measuring the state
of photon a) and immediately after at wing B (measuring
the entangled state of photon b). A and B must be
*very* close. S is the source of entangled photons.

_________S_____________________ A
|
|
|_______________________________ B

So we can say that for signaling we need
two different observers.

Dirk Bruere at NeoPax

Tom Roberts wrote:
>
> No. The entangled state of the photons does not include such modulation.
> Remember that frequency is NOT an intrinsic property of a photon.

It's not?
How can that be if it has a specific energy?
E = hf?

--
Dirk

http://www.transcendence.me.uk/ - Transcendence UK
http://www.theconsensus.org/ - A UK political party
http://www.onetribe.me.uk/wordpress/?cat=5 - Our podcasts on weird stuff

Tom Roberts

Dirk Bruere at NeoPax wrote:
> Tom Roberts wrote:
>> Remember that frequency is NOT an intrinsic property of a photon.
>
> It's not?
> How can that be if it has a specific energy?
> E = hf?

Energy is also not intrinsic to a photon. Energy and frequency are both
relationships between the photon and an observer's coordinate system.

For example, different observers can observe a given light beam with
different energies and frequencies ("Doppler shift"). The same holds for
the individual photons of such a beam, except that only one observer can
see a given photon.

Note that is speaking loosely -- one cannot generally
discuss "individual" photons, as they are quantum objects.