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Detecting "Spooky Action at a Distance" with imperfect detectors

Illustration of new method allowing analysis without assuming perfect detectors. Illustration by Armin Tavakoli.
Tavakoli's findings show that minor detector imperfections can significantly impact steering tests, but a new method adapts for these flaws based on experimental control, allowing analysis without assuming perfect detectors. Illustration: Armin Tavakoli.

Entanglement, once dismissed by Einstein as an impossible phenomenon but later shown to be possible by Nobel Prize-winning physicists, continues to raise questions. How can we know that a particle has been controlled? How can we know that the measurements of entanglement we think we are detecting are not in fact misleading due to inadequate detectors? In a new scientific paper, Armin Tavakoli demonstrates a new universal method that eliminates the occurrence of measurement errors due to faulty detectors.

Albert Einstein famously pointed out that quantum theory predicts a “spooky-action-at-a-distance”. By this, he meant that two quantum particles can have strange relationships that allow one of them to dramatically influence the other – even if they are a galaxy apart. These days, physicists say that one particle can steer the other. 

So how can we know that a particle has been steered? Well, we must detect it through a series of measurements, and this has a basic problem: perfect measurements only exist in theory, not in real life. This opens for the possibility that when we think we are detecting steering, we are actually being misled by our flawed detectors. 

In a recently published paper, Armin Tavakoli shows that very small detector imperfections can lead to surprisingly large errors in standard tests of steering. He then shows how this problem can be solved: a simple and general method is developed to correct any steering test based  on the degree of control the experimenter has over their detector. The better detectors we can muster, the smaller corrections we will need. This means that many past and future steering experiments now can be analyzed without having to assume perfect detector capabilities.

Amin Tavakoli`s article on the Physical Rewiew Letter website. 

Armin Tavakoli´s profile in the  Lund Univerity Research Portal.