Ostrados said:I have a trivial question: when measuring 2 entangled particles A and B, what should be the timing between the measurments to get correct results?
In other words after measuring A how long can we wait before measuring B before its state changes?
Pretty much forever, as long as we keep B isolated so that it doesn't interact with something else before we get around to measuring it.In other words after measuring A how long can we wait before measuring B before its state changes?
Karolus said:the B of particle status changes instantaneously to the change of the particle A.
I think my question was misunderstood maybe the word "timing" was misleading, what I mean is time period between measurements, ex if I measure A, then should I measure B within 1 second to get an accurate result?DrChinese said:It doesn't make any observable different which is measured first, or generally the timing.
Nugatory said:Pretty much forever, as long as we keep B isolated so that it doesn't interact with something else before we get around to measuring it.
Makes no difference, although I am a bit perplexed by your usage of 'accurate result'. What do you mean by writing that?Ostrados said:I think my question was misunderstood maybe the word "timing" was misleading, what I mean is time period between measurements, ex if I measure A, then should I measure B within 1 second to get an accurate result?
StevieTNZ said:Makes no difference, although I am a bit perplexed by your usage of 'accurate result'. What do you mean by writing that?
That depends on the nature of the interaction with the mirror that's doing the reflecting. But if you put a detector on the moon (or alpha centauri, or the Andromeda galaxy, or ...) and that detector is making the first interaction the entangled particle undergoes, then yes, you will find the correlations predicted by quantum mechanics.Ostrados said:I measured A then I sent B to the moon and reflected it back then measured it.. will I still get the expected result?
Ostrados said:Lol no you still don't get my question (my bad actually I phrased it wrongly).
I measured A then I sent B to the moon and reflected it back then measured it.. will I still get the expected result?
In other words If I am making an experiment setup, how long can I wait between the 2 measurments?
[QUOTE="bahamagreen said:Just wondering... Doesn't confirmation of both A and B states always occur "inside a light cone"?
If the status of B at A is not known until a measurement value of B is received by A via <c delivery,
how is "instantaneously" not counterfactual definite?
Karolus said:In addition there is another complication due to the fact that the experiment, rather than directly measure a non-local correlation, refutes the Bell's Theorem, built as a description to "local variables." Let's say that if it were true Theorem would expect a certain statistical value of the correlations, we assume:> TOT. However, the experiments show that the correlation statistic is <= TOT. Then the theorem is refuted, then it is wrong the assumption that there are local variables, then there is a non-local correlation. really reduced to minimum terms .
DrChinese said:Sidebar on terminology: Bell's Theorem usually leads to an inequality when one assumes Local Realism. The inequality is violated, which refutes Local Realism. Bell's Theorem is not refuted in that process.
Karolus said:Then A is automatically sure, without checking, that B has measured "-".
...the correlation must in fact be verified...
A's measurement is not "peculiar" in any way no matter what happens with B; it is impossible for A to even know that he was a measuring particles from a bunch of spin-entangled pairs until after he compares his results with B's after the fact. (If there's not a bunch of pairs, just one, then there is no way for either A or B to ever know the pair was entangled).bahamagreen said:This would suggest that if distant B happened to become destroyed that A could not immediately know (A's measurement would not be "peculiar" in any way).
That's not quite right. A is not automatically sure, without checking, that B has measured "-". A is sure that if B does decide to make an measurement on the same axis then B will measure "-" - but there's no reason to think that B will ever make that measurement or any other, and the only way to find out is to wait around for a while and see if we can get together with B and compare notes.Then A is automatically sure, without checking, that B has measured "-".
DrChinese said:As I said before, generally the timing is not a factor. Experiments have been done with a 1 hour delay. That done using a special (obviously) holding device.
http://lanl.arxiv.org/abs/1006.4344
Entanglement is a striking feature of quantum mechanics and an essential ingredient in most applications in quantum information. Typically, coupling of a system to an environment inhibits entanglement, particularly in macroscopic systems. Here we report on an experiment, where dissipation continuously generates entanglement between two macroscopic objects. This is achieved by engineering the dissipation using laser- and magnetic fields, and leads to robust event-ready entanglement maintained for 0.04s at room temperature. Our system consists of two ensembles containing about 10^{12} atoms and separated by 0.5m coupled to the environment composed of the vacuum modes of the electromagnetic field. By combining the dissipative mechanism with a continuous measurement, steady state entanglement is continuously generated and observed for up to an hour.
bahamagreen said:If entanglement may not be employed for faster than c communications, this would suggest that if distant B happened to become destroyed that A could not immediately know (A's measurement would not be "peculiar" in any way). If A proceeds with the experiment at his end and measures "+", then A is automatically sure, without checking, that B has measured "-", yet B was destroyed before its scheduled measuring time.
Exactly. Destruction cannot be accomplished without an interaction and the interaction effectively measures the state of B and thus determines the state of A.Ostrados said:I think if B was destroyed then the states of A & B will be set at the same moment, for example if we are talking about photons then destroying B means that the photon was absorbed which is equivalent to measurement, then the state of A will be set at the moment of destroying B.
Entanglement measurement timing refers to the precise timing at which measurements are taken on entangled particles. This is important because the timing can affect the results of the measurements and the overall entanglement of the particles.
Timing is important because entangled particles can become unentangled if measurements are taken at different times. This can lead to inaccurate results and can affect the ability to use entanglement for quantum information processing.
Timing can be controlled through various methods such as using synchronized clocks, entangling particles in a controlled environment, and using techniques like quantum teleportation to ensure measurements are taken simultaneously.
Yes, timing can affect the entanglement of particles. If measurements are taken at different times, it can cause the particles to become unentangled and thus affect their level of entanglement.
Yes, there are challenges in timing entanglement measurements. These include the difficulty of synchronizing clocks and the potential for external factors such as noise to disrupt the timing of measurements.