Chapter 3

The micro world

3.5 Quantum entanglement

Another fundamental manifestation of the horizon of cognition is the phenomenon of quantum entanglement.

As it is well known, for many years physicists argued about whether or not local realism observed in the macro world also applies in the micro world.

The assumption of local realism implies that

1. each object is only influenced by its immediate surroundings (locality)
2. an object’s properties are real; they exist regardless of whether or not they are observed (realism)

The principle of locality
Imagine we have two quantum particles with a mutual quantum past, a state, in which the quanta influenced each other – for example, two particles created due to the decay of another particle. Two such particles are said to be entangled.

We then separate these two particles. The principle of locality tells us that their properties originated/were determined at the moment their connection originated and that the particles carry these properties with them. Measuring one particle should hence not influence the state of the other particle in any way once they have been separated.

The principle of realism
postulates that each measurable quantity, including the spin¹ of quantum particles, must correspond to “something real” something that exists independent of any observation. The result of any observation (measurement) should hence be given prior to the actual observation and the choice of an observed (measured) quantity should not affect or disturb it.

Scientists spent decades arguing about whether or not local realism is valid. Albert Einstein is one example of an ardent advocate of local realism and named the phenomenon of quantum entanglement “spooky action at a distance”.

But experiments have repeatedly shown that the quantum world manifestations clearly undermine this principle (e.g. [17]). Observations of pairs of entangled particles show that the particles retain their connection after they have been separated regardless of spacetime limitations (!).

In 2015 an ingenious experiment was carried out at Delft University in the Netherlands [17]. The experiment involved nitrogen doping into the carbon crystal lattice of two artificial diamonds. The nitrogen atoms created vacancies in the lattice, places where carbon atoms were “missing” and therefore they attracted and trapped free electrons. The two diamonds were placed 1.28 km apart. The trapped electrons were excited using microwave pulses, i.e. they were given energy that was immediately released by emitting “their” photons carrying information about their spin. The photons from the two crystals were brought together by optical fibres on a beam splitter (where they interfered) and then they were detected (= observed close up). The interference/detection caused the photons to entangle - and this caused the original electrons, which emitted these photons, to entangle as well (the information about the electrons’ spin orientation was entangled). Immediately after the photons had entangled the electrons, the spin orientation of the electrons in the crystals was quickly measured in random directions. To make sure that there was no unknown “interconnecting” signal propagating between the two diamonds, the electrons’ spin orientation has been measured for a mere 3.7 microseconds (it would take 4.27 microseconds for light to transmit information at such a distance). This measurement showed that there is a statistically significant correlation between the measured spin orientations of the electrons in the two crystals.

So, it was observed, that measuring one of the entangled particles immediately affects the behaviour (the measurement results) of the other (however far apart they may be). It seems that any time or space limitations are cancelled out, as if the electrons agreed that each time they would orient their spins in mutually opposite directions.

It is thus possible that the electron’s spin orientation is “randomly” determined the moment it is measured (and not defined earlier), but that would undermine the principle of realism.

If the electrons’ spin orientation were real, the electrons would have to communicate at a speed faster than the speed of light (the electrons measured in one crystal would instantly have to “notify” the electrons in the other crystal so that it made sure they had the opposite spin orientation). Yet such “instant, faster-than-the-speed-of-light” communication undermines the principle of locality.

Further research is (fairly successfully, see [38]) trying to find a way to keep the particles entangled for sufficiently longer time (so that the entanglement is not disrupted by external interactions, or so that it is renewed faster than it is lost). A quantum network based on this phenomenon could be a revolutionary step for information transfer.

But in any case, the results show that the principle of local realism is not tenable in the micro world.

How can this be explained?

Everything in our world follows the law of analogy (as everything that exists was created through division, i.e. according to same laws and principles), which is manifested in time, spatial and dynamic similarity of things, forms, events and processes. And so a rippled liquid surface simulates the wave processes of quantum mechanics, and the same mechanisms that make shoelaces come undone can be applied to DNA or other microstructures that fail under dynamic forces, etc.

As mentioned previously, philosophical observation tells us that the entire world originated in a point zero in time and space. In our view, this "0" (point zero) split (and will again unite one day). We can compare this to a fan, that opens in a causal process, so that it can be perceived, and then folds back up. And yet, in timelessness the fan simultaneously exists in both an open and a folded state.

It is a unity that split into two poles, poles that always have the same essence but opposite signs (polarities), i.e. a unity that split into duality.

Before this point split, it was impossible to perceive either time or space (both existed, but in a non-manifested, “folded” state - a state in which all times and spaces were encompassed all at once).

In our perception there is the horizon of cognition, a cut-off point that limits the possibilities of our perception. As we know, the horizon of cognition sets the boundary beyond which time and space do not exist for us (we cannot perceive them).

And as our world is so fond of analogies, the horizon of cognition appears somewhat similar to point zero, the point that everything we know came from – including all its further manifestations.

Particles are at our horizon of cognition, which makes them undistinguishable to us. So, we must first ask ourselves to what extent a particle’s spin is a real and true property of the particle itself. Is it not just a resonant manifestation of its actual own rotation that is incognizable (the horizon of cognition causes we cannot find this out) to us?

It is likely that, although the spin of a particle with a non-zero rest mass is most likely a very real and existing property (everything in the universe rotates around its own axis), to us distant observers the real orientation remains unknown = it remains hidden in the resonant image of all the particle’s possible rotational states. The experimental setup then merely “chooses” from the set of these states (for more information about spin measurement see, for example, the Stern–Gerlach experiment from 1922 [39], where spins of particles were measured by sending the particles through an inhomogeneous magnetic field). This should also be valid for measurement of the spin/polarisation of light quanta – photons (although in this case it is difficult to talk about a real rotation in the sense of a material object).

As we know, the measurement of a spin along a given axis temporarily cancels out the spin’s uncertainty along this axis. By repeatedly measuring along the same axis we get the same results (whether we measure a single particle or two entangled particles), yet we do not know anything about the spin values along the other axes. However, if we subsequently measure the spin along a different axis, we lose the information about the spin along the first axis. This is fully analogical to repeatedly measuring a particle’s position “x”, while not knowing anything about its momentum “p”. Measuring the momentum “p”, we lose the information about its position “x”, according to Heisenberg’s uncertainty principle (1.1).

Measuring the spin orientation along one axis involves “choosing” one of the possible orientations of the actually existing property, but most likely we still do not move the observer towards the particle itself and so we do not know anything about its actual rotational axis (!). It remains incognizable to us, hidden among all the possible states.

This is how the observed “randomness”, which seems to violate the principle of realism, arises.

If we create a pair of entangled particles, which we subsequently separate, what we are actually creating is a process of transition from one state to another, similar to the state of an undivided unity (that is created through entanglement, and is somehow analogical to point zero) becoming a state of duality. So, our experiment divides an undivided unity and the division always creates counterparts. In our case these counterparts necessarily manifest themselves in the opposite signs of the spin orientations of the created poles (here of the two electrons). The distance between the poles is of no importance.

However, if we make the value of one of the poles, uncertain (either ourselves or by external interactions), the value of the other pole must inherently also become uncertain (we return to the state analogical to point zero). If we measure the pole again and get a different value (since to us distant observers the spin orientation oscillates between all its possible positions according to the law of uncertainty), we can be sure that the counterpart will again remain the counterpart.

But this is only our observation, though it manifests itself this way in the (geometrical, quantum, force) consequences of the measured spin orientation.

Since this is a manifestation of the horizon of cognition, here too, quantum entanglement would probably completely disappear if we were able to observe the particles (their measured property - the spin) close up.

Do you think that the reasoning presented above could lead us back to Albert Einstein’s (abandoned) notion of local realism?

Or could it be that (figuratively speaking) our experiments, rather than the stars, merely observe their resonant “reflection” on the rippled surface of water, and so it seems to us that they flicker and form waves in the same (contradictory) spin rhythm?

Can something that is most likely not true actually be true?

¹A spin is a quantum property of particles that does not have an apparent equivalent in the macro world. It is an “intrinsic angular momentum” (similar to a hidden rotation around an axis), which is added to the total angular momentum of a given quantum system. The Spin may take integer or half integer multiples of Planck’s constant. A given particle’s spin always has the same absolute value and only its sign (axial orientation) changes. Depending on their spin, particles (or composite particles e.g. atom nuclei) can be either fermions (with half-integer spin e.g. electrons) or bosons (with integer spin, e.g. photons). Fermions are basic particles of matter (a quantum system, such as an atom, cannot contain two fermions that occupy, share the same quantum state – i.e. they occupy higher and higher energy levels and “take up space”), whereas bosons are force carriers (they can share the same quantum state). The spin of charged particles (e.g. electrons) is connected to its magnetic dipole moment, which enables us to determine its orientation. In ordinary materials, the dipole moments of whole atoms (the sums of the spin and orbital angular momentum) are randomly orientated and they cancel each other out. In ferromagnetic materials they are mutually aligned at room temperature and the material behaves like a classic magnet. In light quanta (photons) the spin orientation can be observed as light polarisation.