Spooky Experiment on ISS Could Pioneer New Quantum Communications Network

With its 180 degree views of Earth and space, the ISS’s cupola is the perfect place for photography. But Austrian researchers want to use the unique and panoramic platform to test the limits of “spooky action at distance” in hopes of creating a new quantum communications network.

In a new study published April 9, 2012 in the New Journal of Physics, a group of Austrian researchers propose equipping the camera that is already aboard the ISS — the Nikon 400 mm NightPOD camera — with an optical receiver that would be key to performing the first-ever quantum optics experiment in space. The NightPOD camera faces the ground in the cupola and can track ground targets for up to 70 seconds allowing researchers to bounce a secret encryption key across longer distances than currently possible with optical fiber networks on Earth.

“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.

Albert Einstein first coined the phrase ‘spooky action at a distance’ during his philosophical battles with Neils Bohr in the 1930s to explain his frustration with the inadequacies of the new theory called quantum mechanics. Quantum mechanics explains actions on the tiniest scales in the domain of atoms and elemental particles. While classical physics explains motion, matter and energy on the level that we can see, 19th century scientists observed phenomena in both the macro and micro world that could not easily explained using classical physics.

In particular, Einstein was dissatisfied with the idea of entanglement. Entanglement occurs when two particles are so deeply connected that they share the same existence; meaning that they share the same mathematical relationships of position, spin, momentum and polarization. This could happen when two particles are created at the same point and instant in spacetime. Over time, as the two particles become widely separated in space, even by light-years, quantum mechanics suggests that a measurement of one would immediately impact the other. Einstein was quick to point out that this violated the universal speed limit set out by special relativity. It was this paradox Einstein referred to as spooky action.

CERN physicist John Bell partially resolved this mystery in 1964 by coming up with the idea of non-local phenomena. While entanglement allows one particle to be instantaneously influenced by its exact counterpart, the flow of classical information does not travel faster than light.

The orbital pass of the ISS over an optical ground station could be used for quantum communication from inside the Cupola Module, as long as the OGS is not more than 36° off the NADIR direction. Credit: T Scheidl, E Wille and R Ursin.
The orbital pass of the ISS over an optical ground station could be used for quantum communication from inside the Cupola Module, as long as the OGS is not more than 36° off the NADIR direction. Credit: T Scheidl, E Wille and R Ursin.
The ISS experiment proposes using a “Bell experiment” to test the theoretical contradiction between predictions in quantum and classical physics. For the Bell experiment, a pair of entangled photons 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. So far, researchers sent a secret key to receivers just a few hundred kilometers apart.

“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,” says Ursin. “Our experiments will also enable us to test potential effects gravity may have on quantum entanglement.”

The researchers point out that making the minor alteration to a camera already aboard the ISS will save time and money needed to build a series of satellites to test researchers’ ideas.

13 Replies to “Spooky Experiment on ISS Could Pioneer New Quantum Communications Network”

  1. This is so exciting. A colleague at MIT explained to me the benefits just in the medical field alone. There will be many other disciplines benefiting w/helping man kind. …take care all.

  2. This doesn’t make sense. As I understand it, quantum entanglement can’t be used for communications, period. Yes, the spins on the particles are in synch, but they also fluctuate randomly. Any attempt to change that spin would, by definition, break the entanglement.

    1. One can teleport states. Alice and Bob at different locations can have their pair in an entanglement. Bob can then entangle his state with another, and perform a transformation that replaces Alices with this new state. Alice’s however has no knowledge of it. Bob must then send a classical signal, at or slower than the speed of light, so that Alice can orient her measurement apparatus to materialize this state.

    2. And, as has been recently shown, you can recover the correlated pair observable statistically by weak measurements despite measuring the other one strongly before that.

      So as long as you can prepare and transfer massive amounts of particles, you can at some decreased efficiency get around measurement problems (in a statistically meaningful way).

  3. This seems confused.

    First, that Einstein disliked the concept of entanglement so much that he used Newton’s “action at a distance” concept in a deriding way doesn’t mean that there is an action that follows an action (energy) principle. Since entanglement isn’t breaking causality, there is no information flowing at speeds above the universal speed limit, means there is no energy flowing at such speeds.

    Einsteins derisive concept has been shown to be erroneous and should be retired to avoid confusion. Re “test the limits of “spooky action at distance””, there is no such test. But they will be testing entanglement, how composite quantum systems works under measurements.

    Second, composite systems share the same state, not “the same existence”. This is no different from gas molecules in the a room sharing the same (macro) state. When measurements are done the correlations are shared, but the companion systems parts (say, particles) are not “impacted”. Re “the two particles become widely separated … a measurement of one would immediately impact the other”, “one particle to be instantaneously influenced by its exact counterpart”.

    It is the systems that are impacted through the correlations, the measurements are done on the whole, non-local, systems.

    Third, I don’t know if Bell came up with an idea of non-locality. (I need to read the paper.) He wanted to rule out local hidden variables, and tests based on his theorems validates that.

    In realist versions of quantum mechanics realism is preserved and locality may be preserved (say, in many worlds theory). What is sacrificed is the way realism works, often by not attributing reality to quantum characteristics of a system before they are measured. This resolves ideas of “particle-wave” dualism in favor of systems like quantum fields.

    FWIW, as far as I understand Penrose’s twistor space formalism the twistor space, which preserves locality and is the “real” space, maps to a sometimes non-local spacetime that is emergent from relativity and quantum mechanics combined.

    1. In reference to twistor theory this is a somewhat different meaning to locality. Quantum field theories impose harmonic oscillators at every point on a spatial manifold. These oscillators are outside of each other’s light cone and so the commutators between them are zero. In that sense quantum field theory is local, and this locality permits the computation of two point functions, propagators and the rest. Twistor theory involves a bispinor (x^a, ?_a) where these are conjugate variables. The position part of the twistor evolves as

      x’^a = x^a + X^{aa’}?_a’

      which defines the causality condition between different spinors. This equation is a fancy spinor form of x = x_0 + vt. In that sense twistor theory is every bit as much as local as other QFTs

      Quantum nonlocality involves entanglements between states. Quantum states are constructed from quantum field as operators on a Fock space, which is a space of elementary occupation levels. Quantum oscillators at different regions of space are completely local, but they can construct states that are in nonlocal entanglements.

      General relativity is a geometric theory of spacetime, which means that quantum gravity means quantizing spacetime itself. It is not entirely clear what this means. A number of questions have to answered, and currently there are obstacles in our current theories which do not permit us to address these issues well. Standard quantum field theory is local, but the fundamental physical observables of quantum gravity, which means diffeomorphism-invariant, are necessarily nonlocal. Quantum mechanics is nonlocal, but the wave function is defined by the action of field operators that act on a Fock space so as to define an amplitude locally. In a related manner quantum field theory takes causality as a fundamental postulate, but in quantum gravity the spacetime geometry, and thus the light cones and the causal structure, are subject to quantum fluctuations. This has the curious meaning that a quantum field is propagating on spacetime, but where spacetime is the quantum field.


    2. i wonder how many people have taken the time to see what he meant by “spooky action.” it’s the kind of phrase that spurs curiosity.

      1. I agree, along with quantum weirdness which only tells us that physicists have absolutely no idea how to explain non-local interactions. And upon this so much weird stuff follows: quantum teleportation to mention one absurd idea. Get real. No, rather get locally real.

  4. Why not do the experiment on opposite sides of Earth? It seems they already have to move one of the entangled particles thousands of kilometers to get it launched to the ISS. I smell expensive taxpayer-funded grandstanding.

  5. A Bell type experiment gets clarified when we realize that the transverse vector direction of polarization of photons, traveling along a ray of linearly polarized light, is not confined to a single plane of vibration, but has an angular spread of 90 degrees.
    Linear Polarization, Graphical Representation

  6. Article says: “Quantum mechanics explains actions on the tiniest scales in the domain of atoms and elemental particles.”

    Wrong: quantum mechanics fails to predict if a spin will be deflected up or down in a Stern Gerlach Experiment. or if a single photon will be transmitted or absorbed by a polarizer.

    Article says: “Over time, as the two particles become widely separated in space, even by light-years, quantum mechanics suggests that a measurement of one would immediately impact the other.

    Although this is the Party Line, it makes absolutely no physical or logical sense. If you ask people how this happens, they say “spooky” (read above) or “weird”. If you are honest with yourselves you are basing a lot of stuff on entanglement and nobody has any idea how the connectivity between space-like separated particles maintain connected. “quantum channels: quantum poppycock”

    The experiment suggested here will no doubt work, but not because of non-local interactions. See more on blog:http://quantummechanics.mchmultimedia.com/

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