I am covering a recent bit of Science news reported in Nature. It has to do with "spooky action at a distance". I had studied this quantum mechanics phenomena under Prof. Alain Aspect (not kidding you on the name) while at the Polytechnique School in Paris. So when I saw him pen the coverage of the research I was somewhat excited. Prof Aspect is famous for an experiment done in the 80's whose results violate Bell's inequalities and confirm predictions of Quantum Mechanics instead.
First hypothesized by Einstein, Podolski and Rosen, this class of "thought experiment" was about pointing out a weird prediction that spooky action at a distance was predicted with particles in a Quantum state called "entangled". Einstein famously did not believe in this possibility.
Since then, a lot of observed data has dodgedly confirmed the QM predictions to the dismay of many physicists. As Alain Aspect puts it in the "news and view" coverage of the new research in Nature "one has to wonder what a scientist like Einstein would have to say knowing what we know today".
Special relativity tells us that the speed of light is finite (and constant). Point A and B can communicate exchanging light within the time it takes for that light to travel from point A to point B.
Now, take 2 photons that are entangled, intermingling at a point in time so their quantum state obey a conservation law down the road. Now, the trick is that you let the photons fly apart to a point where they cannot communicate any longer at the time of measurement: A and B are so far apart that they cannot exchange photons in the time it takes to do the measurements. In theory they are separated: that is "locality".
EPR introduced the notion of "hidden variables" take 2 cards, a queen and a king, they are "entangled" if you see a queen you know the other one is a king and vice-versa. So when you let the card "travel" and you observe a "king" it is not because communication took place just because that is what your cards are. That is "realism".
Realism can be translated in a series of inequalities, first derived by Bell that give you measurable quantities. The experiments under discussion violate those inequalities, essentially pointing to 'instanteneous communication" between particles far apart. Are we to believe that information was carried faster than the speed of light? Esentially at once?
Saving both Realism and Locality
Which concept is at fault? Realism or Locality? Locality is a cause of the finite speed of light. The assumption here is "speed of light is finite". Since we observe spin, I assume a "reality" to that dimension. It may be wrong but for all I know, facts agree with this interpretation. Realism starts encompassing more dimensions than the ones we experience and observe as humans (4D: time and space). Expanded realism takes as realm "dimensions" of spin.
In this quantum space, the state of the particles never "drifts" apart, they are entangled, they are physically connected and information exchange can take place in that space. If it does, it may very well obey the laws of locality, i.e finite speed of information.
Furthermore, maybe the laws of locality have no sense at all in the geometry of spin, there is no notion of "space of points" like 3D realism but rather a vectorial space of a quantum variables. Whatever it is, this instant communication, is observed, can we leverage it?
Aspect calls, towards the end of his article, for a leap to technical applications of the effect. It is a tall order :) If the effect is so pervasive, what is truly exciting is that we have the technology, at least in the lab, to interact with this sub-world.
One application is network communications. If the results above can be scaled from lab distances to span continents, then we have zero latency across vast distances. Zero latency caches would be buildable with such a technology enabling instant and synchronous state. Is this truly valuable in computing? maybe, you tell me! Are there applications that absolutely require zero latency (databases?).
One application could be with clocks or primary key generation. This would be a way to build a master clock that is always synchronized, worldwide. Or a way to assign IDs that are truly guaranteed unique.
It seems however that from that point of view, applications in networking are far fetched for now, after all latency on earth is on the order of 100ms? for intercontinental communication? this is perfectly acceptable for most applications. Again, any class of practical problem that suffers from the presence of latency would get a boost from this technology.
The benefits of this technology become intuitive when you think about space communication. For those of you that have read "Ender's game" this is how you build the machine that enables instant communication across galaxies. In spite of limited speed of light you can have immediate reach across space from point A to point B. All you need is entangled particles on both ends which implies a source somewhere in the geometrical center, you perform operations on one end and supposedly it affects the particle on the other end, essentially establishing instanteneous information transfer.
So a center emits tangled particles, this is equivalent to a physical link between the two points, say moon and earth, and as soon as a continuous flow of entangled photons takes place, you can start communicating with the other point in real time. You have achieved instanteneous communication in your 3D world, by taking a shortcut through the quantum dimension.
Still in the Sci-fi approach, this result says that Nature has ways of communicating through quantum portals as it where. It has been hypothesized elsewhere that brain cells may contain quantum equipment, both to emit and detect. And that essentially quantum computation is involved in thought. If that is true then the brain cells have built-in technology to interact with the quantum world. It would be cool to harness the proteins and DNA that are responsible for encoding these devices, if they exist. Hijack that code, improve on it, with a rapid evolution design as covered in a previous blog and you have cheap ass, mass manufactured QM equipment.
Like many shamans and whitches have intuitively known in the past, "Spooky action at a distance" is a fact of life, just now do we start having the technology