A practical guide to faster than light communication

reply to post by mbkennel


The reason you quoted the thought experiment and not the actual experiment because the actual experiment says entanglement swapping was CONFIRMED because of strong correlation between photons 1&4. It also gave you the values that were confirmed between 1&4 in the 3 bases.

Everything that's proposed in the thought experiment isn't realized in the actual experiment but the actual experiment captures the heart of the thought experiment which was on delayed choice entanglement swapping.

So of course it's a dodge to run back to the thought experiment from 1999 instead of quoting the actual realization of the thought experiment in 2012.

reply to post by neoholographic


Yes, we understand that. The point is that the computations which show entanglement or not are only possible knowing Victor's data, and are not uniquely determined exclusively by measuring A&B without any knowledge of V.

The effect is still extremely weird, but it's not FTL comm.

You asked me to read the new paper, and I did. It's still the same.

arxiv.org...

In our experiment, the primary events are the polarization measurements of photons 1 and 4 by Alice and
Bob. They keep their data sets for future evaluation. Each of these data sets by itself and their correlations are
completely random and show no structure whatsoever. The other two photons (photons 2 and 3) are delayed
until after Alice and Bob’s measurements, and sent to Victor for measurement. His measurement then decides
the context and determines the interpretation of Alice and Bob’s data

According to Victor’s choice of measurement (i.e. entangled or separable state) and his results (i.e. |Φ+〉23,
|Φ−〉23, or |𝐻𝐻〉23, |𝑉𝑉〉23), Alice and Bob can sort their already recorded data into 4 subsets

It's made explicit that Victor's choice results are needed to correctly interpret A&B's previously recorded data. Therefore, measuring data only on A&B's side, without knowledge of what V did and measured, it is not possible to discern a "bit" corresponding to whether entanglement choice by V was made.

reply to post by mbkennel


When you quote these things out of context, you tell a half truth. Here's more:

In our experiment, the primary events are the polarization measurements of photons 1 and 4 by Alice and Bob. They keep their data sets for future evaluation. Each of these data sets by itself and their correlations are completely random and show no structure whatsoever. The other two photons (photons 2 and 3) are delayed until after Alice and Bob’s measurements, and sent to Victor for measurement. His measurement then decides the context and determines the interpretation of Alice and Bob’s data. In our setup, using two-photon measurement which projects photons 2 and 3 either onto |Φ+〉23 or onto |Φ− 〉23 . This would swap entanglements onto photons 1 and 4. Instead of a Bell measurement, Victor may perform a Bell-state polarization of these photons individually and project photons 2 and 3 either onto |HH〉23 or onto |VV〉23 ,entanglement to photons 1 and 4. Instead of a Bell-state measurement, Victor could also decide to measure the polarization of these photons individually and project photons 2 and 3 either onto HH 23 or onto VV 23 which would result in a well-defined polarization for photons 1 and 4, i.e. a separable state.

According to Victor’s choice of measurement (i.e. entangled or separable state) and his results (i.e. |Φ+ 〉23 ,
|Φ− 〉23 , or |HH〉23 , |VV〉23 ), Alice and Bob can sort their already recorded data into 4 subsets. They can now verify that when Victor projected his photons onto an entangled state (|Φ+ 〉23 or |Φ− 〉23), each of their joint subsets behaves as if it consisted of entangled pairs of distant photons. When Victor projected his photons on a separable state (|HH〉23 or |VV〉23 ) Alice and Bob's joint subsets behave as if they consisted of separable pairs of photons. Whether Alice and Bob's earlier measurement outcomes indicate entanglement of photons 1 and 4 strictly depends on which measurements Victor performs
at a later time on photons 2 and 3.

Again, you're getting mixed up with entanglement swapping and the delayed choice aspect of the experiment. Let me break it down:

When the experiment starts. Photons 1&4 that are with Alice and Bob are measured and they don't show any entanglement because photons 1&4 haven't interacted. So of course photons 1&4 are completely random at this point.

Next photons 2&3 are sent to Victor. Remember, photons 1&2 and 3&4 are entangled. This gets to the entanglement swapping portion of the experiment. Victor gets photons 2&3 after Alice and Bob have measured photons 1&4. He then makes a measurement on photons 2&3 that determine if entanglement swapping has or hasn't occurred.

THE ONLY REASON YOU NEED VICTORS RESULTS IS TO CONFIRM THE DELAYED CHOICE PORTION OF THIS EXPERIMENT.

You don't need Victors results to determine if entanglement swapping has occurred on photons 1&4.

In the experiment, they were seeing if Victors results still could effect photons 1&4 after photons 1&4 have been measured. You don't need Victors results to send information faster than light or to send information to Alice and Bob.

Think about it, it's really simple.

In the delayed choice portion, Alice and Bob will be making a measurement before Victor makes his measurement. When sending information, Alice and Bob will not measure photons 1&4 until Victor has made his choice to entangle or not to entangle photons 2&3.

Again, you're getting lost in the delayed choice portion of the experiment. Of course Bob and Alice will find complete randomness when they measure photons 1&4 before Victor chooses to entangle or not to entangle photons 2&3.

WHEN SENDING INFORMATION FASTER THAN LIGHT VICTOR WILL CHOOSE TO SWAP ENTANGLEMENT OR NOT SWAP ENTANGLEMENT BEFORE ALICE AND BOB MEASURE PHOTONS 1&4!!

The article tells you that Alice and Bob can know if entanglement swapping has occurred or hasn't occured by measuring photons 1&4.

When Victor performs a Bell state measurement this swaps entanglement which is CONFIRMED by strong correlation between 3 bases for photons 1&4. When this occurs the state fidelity is 0.681+/-0.034 and the entanglement witness value is -0.181+/-0.034 which shows entanglement between photons 1&4.

If Victor chooses a separable state measurement, the state fidelity is 0.421+/-0.029 and the entanglement witness value is 0.078+/-0.029 between photons 1&4.

IMPORTANT POINT:

WHEN VICTOR CHOOSES A BELL STATE MEASUREMENT ON PHOTONS 2&3 STRONG CORRELATION ON ALL 3 BASES OCCURS BETWEEN PHOTONS 1&4. WHEN VICTOR CHOOSES A SEPARABLE STATE MEASUREMENT OR NOT TO SWAP ENTANGLEMENT, CORRELATION OCCURS ON ONE OF THE 3 BASES BETWEEN PHOTONS 1&4!!

To sum it up one more time and this is why you have to read the entire paper instead of looking for parts to quote out of context.

When sending information faster than light Victor chooses to swap or not swap entanglement before Alice and Bob measure photons 1&4. When carrying out the delayed choice portion of the experiment, Victor measures Photons 2&3 after Alice and Bob measure photons 1&4.

reply to post by neoholographic


Are you unable to read?

The other two photons (photons 2 and 3) are delayed until after Alice and Bob’s measurements, and sent to Victor for measurement. His measurement then decides the context and determines the interpretation of Alice and Bob’s data.

THEY HAVE TO SEND THE DATA FIRST.

reply to post by OccamsRazor04


Is there a problem of comprehension here?

DID YOU READ THE PREVIOUS POST???

Of course they have to wait for Victors data in the delayed choice portion of the experiment.

This is because Victor makes his choice to swap entanglement or not swap entanglement after Alice and Bob make a measurement. This will not be the case when Victor sends information to Alice and Bob.

Victor will choose to entangle photons 2&3 before Alice and Bob measure photons 1&4. Of course Alice and Bob have to wait for Victor. That's the whole point of delayed choice but not entanglement swapping.

Again, photons 1&2 and photons 3&4 will first be entangled. You send photons 2&3 to Victor and photons 1&4 stay with Bob and Alice. When sending information:

VICTOR WILL CHOOSE TO SWAP ENTANGLEMENT OR NOT SWAP ENTANGLEMENT BEFORE ALICE AND BOB MEASURE PHOTONS 1&4. IN THE DELAYED CHOICE PORTION OF THE EXPERIMENT VICTOR MAKES HIS CHOICE AFTER BOB AND ALICE HAVE MEASURED PARTICLES 1&4.

It's really not that hard to grasp.

reply to post by neoholographic


Well, you can lead a horse to water .... the truth has been proven over and over. I am done trying to help you.

reply to post by OccamsRazor04


The problem is you have tunnel vision. You can't see past what you already believe.

Like I said, it's simple.

When does Victor choose to swap entanglement? In the delayed-choice experiment he makes a measurement after Alice and Bob make their measurement on photons 1&4. When Victor is sending information to Alice and Bob, he chooses to swap entanglement before Alice and Bob make a measurement.

If you can't grasp that simple difference, it's because you don't want to.

I don't think my insight is useful in science terms but definitely thought provoking.

I am going to make a statement with no evidence but it is logical and I have never seen or heard this anywhere other than from my boss.

I didn't disagree or accept what he said to me but I thought about it and I agreed that:
The comprehension is always quicker/faster than the comprehended.

Anything that can be comprehended, cannot be faster than the comprehension. So if you agree here there is not much argument for my next statement. A laugh from the scientists as well.

My boss said there is one thing faster than light, and I said what, he said thought. I was like wow, how? and he basically said that you can think about been anywhere, and anything instantly, were as light still travels and has a speed, but our thoughts are instantaneous.

"The idea is to create two particle pairs, send one to one computer, the other to another," Zeilinger said."Then if these two photons are entangled, the computers could use them to exchange information."

Like a mind and bodily emotions.

Sorry for the lack of sciences, great post.