‘Spooky’: Did Einstein Get it Wrong?
Einstein has been proven wrong, yet again – at least on one thing. Second paper proves ‘spooky action at a distance’ is real, contrary to Einstein’s view. The theory riled Einstein as it suggested data could travel faster than light. 
In quantum physics, entangled particles are connected despite distance. This means the action of one will instantly change behaviour of the other. But NIST showed it was possible by separating photon pairs and sending them by fiber optic cable to detectors in distant rooms 184 metres apart.
Einstein called it “spooky” and was referring, specifically, to entanglement – the idea that pairs of sub-atomic particles can be invisibly connected in a way that transcends time and space.
This offended Einstein, since passing information between two points in space faster than the speed of light is supposed to be impossible.
In 1964, the scientist John Stewart Bell devised an experiment designed to rule out hidden variables that could offer a non-weird explanation for ‘action at a distance’.
But all the ‘Bell tests’ performed still contained ‘loopholes’ that, according to critics, could invalidate proof of entanglement.
Now a new paper, which appears in the Physical Review Letters, has provided the most solid proof yet that entanglement does indeed exist.
Researchers at the National Institute of Standards and Technology (NIST) created pairs of identical light particles, or photons, and sent them to two different locations to be measured.
The research team achieved this feat by simultaneously closing all three major ‘loopholes’ that have plagued previous Bell tests.
‘You can’t prove quantum mechanics, but local realism, or hidden local action, is incompatible with our experiment,’ NIST’s Krister Shalm says.
‘Our results agree with what quantum mechanics predicts about the spooky actions shared by entangled particles.’
The NIST paper was submitted to PRL with the paper by the University of Vienna in Austria who used a similar high-efficiency single-photon detector to achieve the same results.
However, NIST says its results are more definitive than those reported recently by researchers at Delft University of Technology in the Netherlands.
The latest experiment was conducted at NIST’s Boulder, Colorado campus.
In the NIST study, the photon source and the two detectors were located in three different, widely separated rooms on the same floor in a large laboratory building.
The two detectors are 184 meters apart, and 126 and 132 meters, respectively, from the photon source.
The source creates a stream of photon pairs through a common process in which a laser beam stimulates a special type of crystal.
This process is generally presumed to create pairs of photons that are entangled, so that the photons’ polarisations are linked with one another.
Polarisation refers to the specific orientation of the photon, like vertical or horizontal.
Photon pairs are then separated and sent by fiber-optic cable to separate detectors in the distant rooms.
DUTCH TEAM BACKS UP RESULTS
A similar experiment was recently performed by a team in the Netherlands.
The Dutch team entangled electrons held in tiny diamond traps 0.8 miles (1.3km) apart on opposite sides of the campus at Delft University.
It then did the Bell test which does a measurement on two sides of an entangled pair choosing randomly between possible ‘questions’ at both sides.
Depending on which question is asked, a different property is measured.
The test used pairs of single electrons, to make sure that all the entangled pairs were measured, allowing the team to close the detection loophole.
The 0.8 miles (1.3km) distance between detectors was also too far to allow light to travel between them in the time it took to ask a question and get an answer. This closed the locality loophole.
If found that the ‘spooky action at a distance’ phenomenon was indeed real. While the photons are in flight, a random number generator picks one of two polarisation settings for each polarisation analyser.
If the photon matched the analyser setting, then it was detected more than 90 per cent of the time.
In the best experimental run, both detectors simultaneously identified photons a total of 6,378 times over a period of 30 minutes.
Other outcomes, such as just one detector firing, accounted for only 5,749 of the 12,127 total relevant events.
Researchers calculated that the maximum chance of local realism producing these results is just 0.0000000059, or about 1 in 170 million.
The NIST experiment closed the three major loopholes which including fair sampling.
hanks to NIST’s single-photon detectors, the experiment was efficient enough to ensure that the detected photons and measurement results were representative of the actual totals.
The detectors, made of superconducting nanowires, were 90 percent efficient, and total system efficiency was about 75 per cent.
There was no faster-than-light communication. The two detectors measured photons from the same pair a few hundreds of nanoseconds apart, finishing more than 40 nanoseconds before any light-speed communication could take place between the detectors.
Detector settings were chosen by random number generators operating outside the light cone of the photon source.
This means there was no chance they could be manipulated.
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