'Spooky action at a distance' aboard the ISS

Apr 09, 2013
International Space Station. Credits: ESA

(Phys.org) —Albert Einstein famously described quantum entanglement as "spooky action at distance"; however, up until now experiments that examine this peculiar aspect of physics have been limited to relatively small distances on Earth.

In a new study published today, 9 April, in the Institute of Physics and German Physical Society's New Journal of Physics, researchers have proposed using the (ISS) to test the limits of this "spooky action" and potentially help to develop the first global network.

Their plans include a so-called Bell experiment which tests the theoretical contradiction between the predictions of and classical physics, and a quantum key distribution experiment which will use the ISS as a relay point to send a secret across much larger distances than have already been achieved using on Earth.

Their calculations show that "major experimental goals" could already be achieved with only a few overhead passes of the ISS, with each of the experiments lasting less than 70 seconds on each pass.

"During a few months a year, the ISS passes five to six times in a row in the correct orientation for us to do our experiments. We envision setting up the experiment for a whole week and therefore having more than enough links to the ISS available," said co-author of the study Professor Rupert Ursin from the Austrian Academy of Sciences.

Furthermore, the only equipment needed aboard the ISS would be a photon detection module which could be sent to the ISS and attached to an already existing motorised commercial photographer's lens (Nikon 400 mm), which sits, always facing the ground, in a 70 cm window in the Cupola Module.

For the Bell experiment, a pair of would be generated on the ground; one would be sent from the ground station to the modified camera aboard the ISS, while the other would be measured locally on the ground for later comparison.

Entangled photons have an intimate connection with each other, even when separated over large distances, which defies the laws of . A measurement on one of the entangled photons in a pair will determine the outcome of the same measurement on the second photon, no matter how far apart they are.

"According to quantum physics, entanglement is independent of distance. Our proposed Bell-type experiment will show that particles are entangled, over large distances—around 500 km—for the very first time in an experiment," continued Professor Ursin.

"Our experiments will also enable us to test potential effects gravity may have on ."

The researchers also propose a quantum key distribution experiment, where a secret cryptographic key is generated using a stream of photons and shared between two parties safe in the knowledge that if an eavesdropper intercepts it, this would be noticed.

Up until now, the furthest a secret key has been sent is just a few hundred kilometres, which would realistically enable communication between just one or two cities.

Research teams from around the world are looking to build quantum satellites that will act as a relay between the two parties, significantly increasing the distance that a secret key could be passed; however, the new research shows that this may be possible by implementing an optical uplink towards the ISS and making a very minor alteration to the camera already on-board.

Explore further: 'Cavity protection effect' helps to conserve quantum information

More information: Quantum optics experiments to the International Space Station ISS: a proposal" T Scheidl et al 2013 New J. Phys. 15 043008. iopscience.iop.org/1367-2630/15/4/043008/article

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EyeNStein
1.4 / 5 (9) Apr 09, 2013
I hope they have some accurate atomic clocks attached to this experiment. As the ISS has a measurably different timeframe it would be interesting how this affects the entanglement. If it collapses will the change happen at your time or mine?
ian_j_allen
3.6 / 5 (5) Apr 09, 2013
The time dilation experienced in orbit in reference to a 'stationary' observer on earth is such that significant deviations are measured only after extensive time in orbit (see GPS satellites). This means that dilation effects occuring over the 70s course of these experiments will be negligible.

Furthermore, entanglement experiments are typically done by measuring first one photon, then another. Checking simultaneity of the collapse is of little practical use as far as building a communications system is concerned.
EyeNStein
2.3 / 5 (9) Apr 09, 2013
I agree that the dilation is small (but measurable using atomic clocks). But I'm still interested to test if the collapse of the wavefunction is tied relative to the time when the entangled photon is received (common duration) or varies with gravity time dilation. (dilated duration). The latter is to be expected, but entanglement doesn't seem to respect time and light speed in a straight forward manner.
ian_j_allen
not rated yet Apr 09, 2013
The actual collapse of the wave function is essentially instantaneous. Furthermore, you can not observe the 'collapse'. You can only make a measurement, and then make a subsequent measurement, both of which affect the wave function. So even if you had some kind of sub-planck pulsed laser that broke the known laws of physics, you wouldnt get meaningful results out as far as 'watching the wave function collapse from superposition to a single function'. And even if you could, the amount of time dilation of this 'event' would be so small, the reference dislacement would have to be moving at essentially c to observe a significant dilation, at which point it is statistically or even physically (once again)impossible to even make the measurement in the first place.
Mike_Massen
1 / 5 (2) Apr 09, 2013
ian_j_allen offered an imprecise notion/argument with
The time dilation experienced in orbit in reference to a 'stationary' observer on earth is such that significant deviations are measured only after extensive time in orbit...
My understanding is several microseconds per orbit (for GPS) what do *you* consider be an 'extensive time' as per your comment please in comparative reference to the speed of the ISS to be able to assess a quantitative difference delivered by relativistic motion ?

Ref:
http://www.astron...gps.html

http://metaresear...vity.asp
EyeNStein
1 / 5 (5) Apr 09, 2013
The actual collapse of the wave function is essentially instantaneous.

But do we know how to define instantaneous across diverging timeframes? w.r.t.the instant the photon arrived or w.r.t the instant the wavefunction collapses? I think I know what to expect (the duration between should be dilated) but has anyone tested it?
ian_j_allen
5 / 5 (3) Apr 09, 2013
Mike Massen : Your own link explains that between general and special relativistic considerations, 53,100 ns of extra time are accrued in a day. There are 86,400 seconds in one day. That equates to just over 1.5 picoseconds per second. There are about 70 seconds in an experiment. That is very close to 0.1 ns of dilated time per experiment.

Less than one nanosecond is entirely neglible for all but the most stringent of experiments. While picosecond resolution studies are possible, the experiment proposed by the OP isnt even physically viable. I stand by my comment, next time do a little of your own math before jumping to your guns.
ian_j_allen
5 / 5 (2) Apr 09, 2013
The actual collapse of the wave function is essentially instantaneous.

But do we know how to define instantaneous across diverging timeframes? w.r.t.the instant the photon arrived or w.r.t the instant the wavefunction collapses? I think I know what to expect (the duration between should be dilated) but has anyone tested it?


There is actually no way to precisely define two events as perfectly instantaneous within a reference frame, furthermore, they will not be instantaneous if observed from any other reference frame.

As for the quantum physics itself, the collapse of the wave function is not time dependent, therefore it is as I said, "essentially" instantaneous though more rigorous models may attempt to attach a time frame to this event. That time frame would still be on the order of the planck scale, which is at the very edge of reality as we understand it.

You also cant observe the collapse as one photon collapses it, the next shows you the wreckage.
Mike_Massen
1.4 / 5 (10) Apr 09, 2013
ian_j_allen knee jerked vociferously without reflection, with this flakey interpretive indicative gem
..I stand by my comment, next time do a little of your own math before jumping to your guns.
You *totally* missed the point ie. Re what YOU might assess re ISS !

You didn't answer the ISS question one bit, instead you criticised & made yourself look foolish in any dialectic by obviously feeling inclined to follow re GPS (for some entertained with linguistic gremlins) but you have *not* answered my ISS question at all, here it is again in case you have real cognitive problems with short term memory (ie My question is re ISS) do you now understand?:-

"...what do *you* consider be an 'extensive time' as per your comment please in comparative reference to the speed of the ISS to be able to assess a quantitative difference delivered by relativistic motion ?"

Try reading next time & focussing, instead of launching into feeble diatribe & obvious defensive ego based criticism, OK ?
BobVila
not rated yet Apr 09, 2013
Well doing some quick maths (estimated but it should be pretty close) I got a Lorentz factor of ~1.00000000033 (its actually less since I ignored the effects of gravity) for the ISS relative to earth and a travel time for a photon at the lowest orbit of .0012 seconds. For the sake of argument (Im really just concerned with the order of magnitude) I approximated the distance at 70 seconds after lowest orbit giving a distance of 654 km and a travel time of 0.0022 seconds. That gives a time difference of~7.3 x10^-11 seconds. That means in theory it could be measured but in practice its incredibly difficult if not impossible. Remember that you cant just watch a wavefunction collapse. All you can do to observe entanglement is measure one, then the other, and see if they are anti-correlated or not. The best photo-multipliers have a response around that time scale, but getting a statistically significant result with all the potential sources of error seems unlikely, but who knows.
ab3a
not rated yet Apr 09, 2013
Could it be used as a relativistic speedometer?
baudrunner
1 / 5 (1) Apr 09, 2013
For the interested, Scientific American reports in a past article from the issue of several years ago dedicated to Albert Einstein that 35 microsecond corrections per 24 hours needed to be made to the onboard clocks of GPS satellites in orbit around Earth to compensate for the relativistic effects of traveling at high velocity and in the absence of gravity. That might not seem like much, but the difference in accuracy of positioning is very significant when these corrections are not made.

I wonder, how would relativistic effects affect an Earth to space ladder, or elevator?
baudrunner
3 / 5 (4) Apr 09, 2013
Here's an exercise for the math wizards out there: calculate the velocity that GPS satellites will require to achieve in order to cancel out those 35 microsecond differences so that their clocks can be synchronized exactly with ground based clocks.
Mike_Massen
not rated yet Apr 10, 2013
In respect of baudrunner's question re 'maths wizards' bear in mind the GPS has to *stay* in orbit to satisfy the condition, once you review the links I supplied earlier:-

http://www.astron...gps.html
and
http://metaresear...vity.asp

The answer should be obvious but could it satisfy staying in orbit ;-)
ant_oacute_nio354
1 / 5 (7) Apr 11, 2013
Einstein was a idiot.
DarkHorse66
5 / 5 (5) Apr 12, 2013
Einstein was a idiot.

Correction: 'Einstein was AN idiot'......
DH66
PS He may not have been perfect (who really is...), but the fact of the (non)-existance of his 'idiocy' is a matter of personal opinion. Besides, Einstein's 'smartness' is NOT what this article is about; so YOU ARE BADLY OFF-TOPIC! (as usual)
Mike_Massen
3.9 / 5 (7) Apr 12, 2013
ant_oacute_nio354 (who hides behind an obverse nickname) made an idiot bark with
Einstein was a idiot.
Why be so pathetic, is it automatic for your nature ?

True scientists and other mature people dont just bark one liners like yours, they offer, at the least, a minimal level of supporting evidence or some intelligent comment which connects with your 'bark'. It need not be an authoritative reference with exemplary detail but at the least some form of rationale, the absence of which, strongly suggests you are not rationale ant_oacute_nio354

ie. Please save time/effort and aggravation for all and 'go somewhere else',

good luck, I fear you will really need it.
jimbo92107
not rated yet Apr 13, 2013
Question: Does quantum entanglement of this kind make it possible to send a "Hello from Earth" message to the moon, and then get a "Hi right back at ya from the Moon" reply with no speed of light delay?

That would be neat.
ValeriaT
1 / 5 (4) Apr 13, 2013
IMO it could be possible if we would send the gravitational wave beam from superconductor accelerated with EM discharge toward superconductor mirror at Moon and detected the reflection. These technologies already exist, but they're not publicly researched, as they do violate the theories of contemporary physical establishment and technology proliferation rules of governments.
antialias_physorg
5 / 5 (4) Apr 13, 2013
IMO it could be possible if we would send the gravitational wave beam from superconductor accelerated with EM discharge toward superconductor mirror at Moon and detected the reflection.

WTF? I know you always just take some random words from a list of scietific terms and plug them togethet in a sentence...but that one just takes the cake.

ValeriaT
1 / 5 (4) Apr 13, 2013
In AWT the vacuum can spread not only transverse waves of light, but the longitudinal waves, which are much faster in similar way, like the longitudinal waves of water are faster than the surface transverse waves. How we can generate the longitudinal waves at the water surface? Well, with floaters, which are allowed to move in vertical direction only. In superconductors the Dirac fermions play a role of such floaters: the electrons which are heavily compressed each other, so they cannot move mutually and only quantum zitterbewegung (jitterbugging ?) is allowed for them (i.e. undulations along time dimension only). Such an objects do reflect and radiate the scalar waves of vacuum preferentially. You should learn a bit about dense aether model to understand it.
ValeriaT
1 / 5 (3) Apr 13, 2013
The scalar waves are emanated with common electromagnetic(EM) circuits, which they don't oscillate, but simply change their field intensity on and off, for example during discharge. Nicola Tesla did use the magnetic extinguishers in his sparks plugs for to minimize the switching time and to increase the radiation of scalar waves into account of the EM ones. When the EM pulse hits the Dirac electrons within superconductor (SC), it breaks their entanglement for a moment and all Cooper pairs within SC will expand fast and collapse again. During this the scalar pulse is radiated in direction of EM pulse. The entangled electrons within SC absorb common EM radiation poorly, but they absorb the scalar waves as easily, as they do radiate it - so they can serve as a mirror for scalar waves in similar way, like the electron within metals do reflect the visible light. The scalar waves do apply to magnetic motors too, as they're not driven with changing of polarity but intensity of magnet field.